Fix comments about return value of grpc_completion_queue_{next,pluck}
Fix comments about return value of grpc_completion_queue_{next,pluck}

sidrakesh93/grpc,vsco/grpc,infinit/grpc,podsvirov/grpc,msiedlarek/grpc,rjshade/grpc,doubi-workshop/grpc,yonglehou/grpc,vjpai/grpc,jcanizales/grpc,jboeuf/grpc,doubi-workshop/grpc,fuchsia-mirror/third_party-grpc,JoeWoo/grpc,deepaklukose/grpc,arkmaxim/grpc,matt-kwong/grpc,ejona86/grpc,yinsu/grpc,MakMukhi/grpc,andrewpollock/grpc,quizlet/grpc,ananthonline/grpc,donnadionne/grpc,donnadionne/grpc,gpndata/grpc,royalharsh/grpc,pmarks-net/grpc,tempbottle/grpc,chrisdunelm/grpc,surround-io/grpc,arkmaxim/grpc,tamihiro/grpc,dklempner/grpc,gpndata/grpc,tengyifei/grpc,msiedlarek/grpc,Crevil/grpc,thinkerou/grpc,muxi/grpc,a-veitch/grpc,matt-kwong/grpc,PeterFaiman/ruby-grpc-minimal,zeliard/grpc,xtopsoft/grpc,royalharsh/grpc,a-veitch/grpc,tamihiro/grpc,yinsu/grpc,tengyifei/grpc,7anner/grpc,mehrdada/grpc,philcleveland/grpc,greasypizza/grpc,royalharsh/grpc,makdharma/grpc,malexzx/grpc,geffzhang/grpc,nicolasnoble/grpc,mehrdada/grpc,yonglehou/grpc,ejona86/grpc,philcleveland/grpc,geffzhang/grpc,surround-io/grpc,soltanmm/grpc,VcamX/grpc,baylabs/grpc,a11r/grpc,soltanmm/grpc,baylabs/grpc,ctiller/grpc,pmarks-net/grpc,kskalski/grpc,sidrakesh93/grpc,daniel-j-born/grpc,maxwell-demon/grpc,kskalski/grpc,yugui/grpc,fuchsia-mirror/third_party-grpc,w4-sjcho/grpc,MakMukhi/grpc,miselin/grpc,ctiller/grpc,jtattermusch/grpc,maxwell-demon/grpc,soltanmm-google/grpc,kriswuollett/grpc,yugui/grpc,royalharsh/grpc,perumaalgoog/grpc,ipylypiv/grpc,ncteisen/grpc,sreecha/grpc,carl-mastrangelo/grpc,kriswuollett/grpc,yongni/grpc,pmarks-net/grpc,ananthonline/grpc,grpc/grpc,yang-g/grpc,ksophocleous/grpc,soltanmm/grpc,murgatroid99/grpc,perumaalgoog/grpc,donnadionne/grpc,tengyifei/grpc,larsonmpdx/grpc,fichter/grpc,grpc/grpc,y-zeng/grpc,vjpai/grpc,vsco/grpc,larsonmpdx/grpc,JoeWoo/grpc,tengyifei/grpc,apolcyn/grpc,greasypizza/grpc,meisterpeeps/grpc,y-zeng/grpc,a-veitch/grpc,crast/grpc,stanley-cheung/grpc,crast/grpc,donnadionne/grpc,philcleveland/grpc,andrewpollock/grpc,doubi-workshop/grpc,grpc/grpc,pszemus/grpc,tengyifei/grpc,nicolasnoble/grpc,yongni/grpc,simonkuang/grpc,bjori/grpc,stanley-cheung/grpc,msiedlarek/grpc,grpc/grpc,greasypizza/grpc,infinit/grpc,pszemus/grpc,bogdandrutu/grpc,apolcyn/grpc,infinit/grpc,ctiller/grpc,jboeuf/grpc,daniel-j-born/grpc,7anner/grpc,ctiller/grpc,fuchsia-mirror/third_party-grpc,leifurhauks/grpc,gpndata/grpc,ipylypiv/grpc,deepaklukose/grpc,perumaalgoog/grpc,msiedlarek/grpc,jtattermusch/grpc,sreecha/grpc,tempbottle/grpc,firebase/grpc,deepaklukose/grpc,msiedlarek/grpc,yonglehou/grpc,geffzhang/grpc,bjori/grpc,miselin/grpc,infinit/grpc,ejona86/grpc,larsonmpdx/grpc,ksophocleous/grpc,xtopsoft/grpc,fuchsia-mirror/third_party-grpc,crast/grpc,Crevil/grpc,LuminateWireless/grpc,simonkuang/grpc,surround-io/grpc,goldenbull/grpc,murgatroid99/grpc,chrisdunelm/grpc,pszemus/grpc,andrewpollock/grpc,dklempner/grpc,cgvarela/grpc,mehrdada/grpc,Crevil/grpc,wkubiak/grpc,perumaalgoog/grpc,philcleveland/grpc,zeliard/grpc,malexzx/grpc,kpayson64/grpc,LuminateWireless/grpc,PeterFaiman/ruby-grpc-minimal,ofrobots/grpc,VcamX/grpc,JoeWoo/grpc,msmania/grpc,baylabs/grpc,sidrakesh93/grpc,Vizerai/grpc,madongfly/grpc,daniel-j-born/grpc,arkmaxim/grpc,mehrdada/grpc,y-zeng/grpc,tengyifei/grpc,crast/grpc,quizlet/grpc,surround-io/grpc,soltanmm-google/grpc,pmarks-net/grpc,ejona86/grpc,chrisdunelm/grpc,w4-sjcho/grpc,miselin/grpc,madongfly/grpc,ppietrasa/grpc,ejona86/grpc,bjori/grpc,daniel-j-born/grpc,firebase/grpc,chrisdunelm/grpc,ppietrasa/grpc,simonkuang/grpc,msiedlarek/grpc,PeterFaiman/ruby-grpc-minimal,tengyifei/grpc,fuchsia-mirror/third_party-grpc,donnadionne/grpc,sreecha/grpc,adelez/grpc,stanley-cheung/grpc,rjshade/grpc,xtopsoft/grpc,sreecha/grpc,madongfly/grpc,ksophocleous/grpc,deepaklukose/grpc,baylabs/grpc,mehrdada/grpc,a11r/grpc,jboeuf/grpc,JoeWoo/grpc,chrisdunelm/grpc,msmania/grpc,chrisdunelm/grpc,soltanmm/grpc,kriswuollett/grpc,PeterFaiman/ruby-grpc-minimal,ppietrasa/grpc,ncteisen/grpc,LuminateWireless/grpc,stanley-cheung/grpc,w4-sjcho/grpc,muxi/grpc,leifurhauks/grpc,ctiller/grpc,hstefan/grpc,malexzx/grpc,dgquintas/grpc,muxi/grpc,xtopsoft/grpc,kriswuollett/grpc,jcanizales/grpc,ofrobots/grpc,adelez/grpc,wkubiak/grpc,kumaralokgithub/grpc,doubi-workshop/grpc,greasypizza/grpc,maxwell-demon/grpc,grpc/grpc,LuminateWireless/grpc,yongni/grpc,kriswuollett/grpc,dgquintas/grpc,a11r/grpc,Vizerai/grpc,murgatroid99/grpc,simonkuang/grpc,sidrakesh93/grpc,geffzhang/grpc,zhimingxie/grpc,leifurhauks/grpc,perumaalgoog/grpc,hstefan/grpc,murgatroid99/grpc,PeterFaiman/ruby-grpc-minimal,JoeWoo/grpc,ananthonline/grpc,7anner/grpc,thunderboltsid/grpc,ipylypiv/grpc,makdharma/grpc,adelez/grpc,surround-io/grpc,ksophocleous/grpc,y-zeng/grpc,kpayson64/grpc,madongfly/grpc,jtattermusch/grpc,soltanmm-google/grpc,carl-mastrangelo/grpc,jtattermusch/grpc,muxi/grpc,ofrobots/grpc,maxwell-demon/grpc,baylabs/grpc,matt-kwong/grpc,simonkuang/grpc,zeliard/grpc,muxi/grpc,kumaralokgithub/grpc,tempbottle/grpc,soltanmm-google/grpc,carl-mastrangelo/grpc,wkubiak/grpc,pszemus/grpc,bogdandrutu/grpc,zhimingxie/grpc,makdharma/grpc,goldenbull/grpc,msmania/grpc,wangyikai/grpc,ejona86/grpc,jtattermusch/grpc,yang-g/grpc,kskalski/grpc,kumaralokgithub/grpc,yinsu/grpc,nicolasnoble/grpc,PeterFaiman/ruby-grpc-minimal,yugui/grpc,wcevans/grpc,mehrdada/grpc,grani/grpc,tempbottle/grpc,wangyikai/grpc,xtopsoft/grpc,Crevil/grpc,firebase/grpc,dklempner/grpc,pszemus/grpc,maxwell-demon/grpc,deepaklukose/grpc,stanley-cheung/grpc,bogdandrutu/grpc,ncteisen/grpc,kumaralokgithub/grpc,tamihiro/grpc,cgvarela/grpc,Crevil/grpc,soltanmm-google/grpc,yinsu/grpc,adelez/grpc,makdharma/grpc,tamihiro/grpc,kskalski/grpc,fuchsia-mirror/third_party-grpc,kpayson64/grpc,a11r/grpc,VcamX/grpc,meisterpeeps/grpc,yongni/grpc,infinit/grpc,thunderboltsid/grpc,ofrobots/grpc,Vizerai/grpc,wcevans/grpc,jtattermusch/grpc,LuminateWireless/grpc,Crevil/grpc,ofrobots/grpc,tamihiro/grpc,yugui/grpc,thinkerou/grpc,chrisdunelm/grpc,malexzx/grpc,arkmaxim/grpc,soltanmm/grpc,tempbottle/grpc,dklempner/grpc,apolcyn/grpc,gpndata/grpc,apolcyn/grpc,bogdandrutu/grpc,bjori/grpc,yang-g/grpc,w4-sjcho/grpc,msmania/grpc,leifurhauks/grpc,wangyikai/grpc,matt-kwong/grpc,arkmaxim/grpc,7anner/grpc,a-veitch/grpc,mehrdada/grpc,muxi/grpc,vjpai/grpc,dgquintas/grpc,vjpai/grpc,jcanizales/grpc,perumaalgoog/grpc,gpndata/grpc,ctiller/grpc,zhimingxie/grpc,y-zeng/grpc,hstefan/grpc,yang-g/grpc,vjpai/grpc,kpayson64/grpc,quizlet/grpc,dgquintas/grpc,hstefan/grpc,ejona86/grpc,grani/grpc,msmania/grpc,a-veitch/grpc,grani/grpc,pmarks-net/grpc,malexzx/grpc,deepaklukose/grpc,ananthonline/grpc,ppietrasa/grpc,ofrobots/grpc,ipylypiv/grpc,greasypizza/grpc,infinit/grpc,chrisdunelm/grpc,yugui/grpc,7anner/grpc,pszemus/grpc,ksophocleous/grpc,daniel-j-born/grpc,bjori/grpc,quizlet/grpc,yonglehou/grpc,sidrakesh93/grpc,fichter/grpc,rjshade/grpc,maxwell-demon/grpc,ananthonline/grpc,kpayson64/grpc,doubi-workshop/grpc,Vizerai/grpc,arkmaxim/grpc,simonkuang/grpc,ctiller/grpc,ksophocleous/grpc,yang-g/grpc,malexzx/grpc,pszemus/grpc,apolcyn/grpc,deepaklukose/grpc,arkmaxim/grpc,zeliard/grpc,madongfly/grpc,deepaklukose/grpc,meisterpeeps/grpc,bogdandrutu/grpc,muxi/grpc,sreecha/grpc,vjpai/grpc,daniel-j-born/grpc,jboeuf/grpc,wangyikai/grpc,pszemus/grpc,chrisdunelm/grpc,podsvirov/grpc,kpayson64/grpc,quizlet/grpc,gpndata/grpc,surround-io/grpc,tengyifei/grpc,y-zeng/grpc,cgvarela/grpc,sreecha/grpc,andrewpollock/grpc,chrisdunelm/grpc,makdharma/grpc,kpayson64/grpc,sreecha/grpc,ctiller/grpc,philcleveland/grpc,yongni/grpc,philcleveland/grpc,hstefan/grpc,grpc/grpc,dklempner/grpc,jcanizales/grpc,tempbottle/grpc,ctiller/grpc,7anner/grpc,msmania/grpc,ncteisen/grpc,PeterFaiman/ruby-grpc-minimal,carl-mastrangelo/grpc,firebase/grpc,ipylypiv/grpc,vsco/grpc,bjori/grpc,pmarks-net/grpc,MakMukhi/grpc,donnadionne/grpc,tengyifei/grpc,kpayson64/grpc,larsonmpdx/grpc,a-veitch/grpc,MakMukhi/grpc,muxi/grpc,leifurhauks/grpc,ejona86/grpc,ncteisen/grpc,yinsu/grpc,mehrdada/grpc,goldenbull/grpc,carl-mastrangelo/grpc,maxwell-demon/grpc,baylabs/grpc,dklempner/grpc,w4-sjcho/grpc,zhimingxie/grpc,jcanizales/grpc,leifurhauks/grpc,thinkerou/grpc,andrewpollock/grpc,leifurhauks/grpc,soltanmm-google/grpc,yongni/grpc,jtattermusch/grpc,wcevans/grpc,murgatroid99/grpc,stanley-cheung/grpc,yinsu/grpc,daniel-j-born/grpc,goldenbull/grpc,miselin/grpc,vsco/grpc,perumaalgoog/grpc,miselin/grpc,bogdandrutu/grpc,kriswuollett/grpc,murgatroid99/grpc,adelez/grpc,fuchsia-mirror/third_party-grpc,yinsu/grpc,fuchsia-mirror/third_party-grpc,yonglehou/grpc,murgatroid99/grpc,yonglehou/grpc,JoeWoo/grpc,grani/grpc,firebase/grpc,dgquintas/grpc,baylabs/grpc,murgatroid99/grpc,wangyikai/grpc,makdharma/grpc,wangyikai/grpc,hstefan/grpc,dgquintas/grpc,kumaralokgithub/grpc,jcanizales/grpc,chrisdunelm/grpc,apolcyn/grpc,meisterpeeps/grpc,ofrobots/grpc,mehrdada/grpc,podsvirov/grpc,mehrdada/grpc,madongfly/grpc,podsvirov/grpc,grpc/grpc,kumaralokgithub/grpc,larsonmpdx/grpc,Vizerai/grpc,sreecha/grpc,thunderboltsid/grpc,apolcyn/grpc,philcleveland/grpc,kskalski/grpc,ctiller/grpc,baylabs/grpc,yonglehou/grpc,kriswuollett/grpc,yongni/grpc,quizlet/grpc,podsvirov/grpc,zhimingxie/grpc,ppietrasa/grpc,firebase/grpc,nicolasnoble/grpc,perumaalgoog/grpc,muxi/grpc,firebase/grpc,JoeWoo/grpc,yongni/grpc,arkmaxim/grpc,fichter/grpc,jboeuf/grpc,rjshade/grpc,jboeuf/grpc,msiedlarek/grpc,ppietrasa/grpc,carl-mastrangelo/grpc,wcevans/grpc,bogdandrutu/grpc,pmarks-net/grpc,sreecha/grpc,sreecha/grpc,VcamX/grpc,adelez/grpc,a11r/grpc,maxwell-demon/grpc,msiedlarek/grpc,bogdandrutu/grpc,yongni/grpc,Crevil/grpc,7anner/grpc,infinit/grpc,andrewpollock/grpc,tamihiro/grpc,a-veitch/grpc,thunderboltsid/grpc,infinit/grpc,geffzhang/grpc,thunderboltsid/grpc,crast/grpc,JoeWoo/grpc,wcevans/grpc,maxwell-demon/grpc,daniel-j-born/grpc,madongfly/grpc,meisterpeeps/grpc,Vizerai/grpc,thinkerou/grpc,grani/grpc,donnadionne/grpc,leifurhauks/grpc,nicolasnoble/grpc,ppietrasa/grpc,quizlet/grpc,yang-g/grpc,podsvirov/grpc,grpc/grpc,thinkerou/grpc,nicolasnoble/grpc,donnadionne/grpc,msmania/grpc,fichter/grpc,quizlet/grpc,doubi-workshop/grpc,Crevil/grpc,jboeuf/grpc,crast/grpc,podsvirov/grpc,simonkuang/grpc,wcevans/grpc,a11r/grpc,dgquintas/grpc,larsonmpdx/grpc,yang-g/grpc,fichter/grpc,xtopsoft/grpc,geffzhang/grpc,bjori/grpc,jboeuf/grpc,ctiller/grpc,y-zeng/grpc,baylabs/grpc,yang-g/grpc,goldenbull/grpc,VcamX/grpc,thinkerou/grpc,xtopsoft/grpc,fichter/grpc,wkubiak/grpc,jtattermusch/grpc,VcamX/grpc,thunderboltsid/grpc,stanley-cheung/grpc,apolcyn/grpc,Vizerai/grpc,thinkerou/grpc,sidrakesh93/grpc,Vizerai/grpc,ejona86/grpc,stanley-cheung/grpc,quizlet/grpc,donnadionne/grpc,goldenbull/grpc,donnadionne/grpc,LuminateWireless/grpc,ananthonline/grpc,vjpai/grpc,tamihiro/grpc,kskalski/grpc,dgquintas/grpc,andrewpollock/grpc,fichter/grpc,msiedlarek/grpc,larsonmpdx/grpc,doubi-workshop/grpc,kpayson64/grpc,grpc/grpc,ipylypiv/grpc,philcleveland/grpc,vsco/grpc,a-veitch/grpc,ipylypiv/grpc,ananthonline/grpc,ppietrasa/grpc,firebase/grpc,meisterpeeps/grpc,matt-kwong/grpc,zhimingxie/grpc,vsco/grpc,zhimingxie/grpc,a11r/grpc,kpayson64/grpc,gpndata/grpc,Vizerai/grpc,w4-sjcho/grpc,ipylypiv/grpc,LuminateWireless/grpc,pszemus/grpc,stanley-cheung/grpc,a11r/grpc,miselin/grpc,ejona86/grpc,podsvirov/grpc,wangyikai/grpc,wkubiak/grpc,y-zeng/grpc,madongfly/grpc,grani/grpc,miselin/grpc,muxi/grpc,matt-kwong/grpc,adelez/grpc,ncteisen/grpc,Vizerai/grpc,vjpai/grpc,thunderboltsid/grpc,JoeWoo/grpc,w4-sjcho/grpc,royalharsh/grpc,MakMukhi/grpc,rjshade/grpc,malexzx/grpc,thinkerou/grpc,w4-sjcho/grpc,greasypizza/grpc,VcamX/grpc,yugui/grpc,VcamX/grpc,grpc/grpc,Crevil/grpc,ncteisen/grpc,thinkerou/grpc,carl-mastrangelo/grpc,kumaralokgithub/grpc,adelez/grpc,ctiller/grpc,yugui/grpc,tamihiro/grpc,hstefan/grpc,wangyikai/grpc,fichter/grpc,kskalski/grpc,zeliard/grpc,stanley-cheung/grpc,royalharsh/grpc,zeliard/grpc,rjshade/grpc,ananthonline/grpc,nicolasnoble/grpc,thinkerou/grpc,yugui/grpc,firebase/grpc,goldenbull/grpc,muxi/grpc,a-veitch/grpc,firebase/grpc,madongfly/grpc,bogdandrutu/grpc,a11r/grpc,matt-kwong/grpc,kumaralokgithub/grpc,andrewpollock/grpc,sidrakesh93/grpc,sreecha/grpc,larsonmpdx/grpc,cgvarela/grpc,dklempner/grpc,soltanmm/grpc,wcevans/grpc,sidrakesh93/grpc,perumaalgoog/grpc,fuchsia-mirror/third_party-grpc,malexzx/grpc,jtattermusch/grpc,vjpai/grpc,w4-sjcho/grpc,greasypizza/grpc,soltanmm-google/grpc,arkmaxim/grpc,mehrdada/grpc,zhimingxie/grpc,cgvarela/grpc,vjpai/grpc,tempbottle/grpc,matt-kwong/grpc,royalharsh/grpc,goldenbull/grpc,ksophocleous/grpc,MakMukhi/grpc,ncteisen/grpc,leifurhauks/grpc,donnadionne/grpc,yinsu/grpc,makdharma/grpc,xtopsoft/grpc,jboeuf/grpc,goldenbull/grpc,7anner/grpc,jtattermusch/grpc,deepaklukose/grpc,surround-io/grpc,kriswuollett/grpc,surround-io/grpc,tempbottle/grpc,soltanmm/grpc,ipylypiv/grpc,LuminateWireless/grpc,murgatroid99/grpc,royalharsh/grpc,hstefan/grpc,jtattermusch/grpc,PeterFaiman/ruby-grpc-minimal,sreecha/grpc,murgatroid99/grpc,carl-mastrangelo/grpc,soltanmm-google/grpc,kskalski/grpc,jboeuf/grpc,hstefan/grpc,grpc/grpc,stanley-cheung/grpc,ksophocleous/grpc,kriswuollett/grpc,ppietrasa/grpc,vsco/grpc,ncteisen/grpc,meisterpeeps/grpc,wkubiak/grpc,geffzhang/grpc,dgquintas/grpc,ncteisen/grpc,PeterFaiman/ruby-grpc-minimal,dgquintas/grpc,malexzx/grpc,crast/grpc,royalharsh/grpc,rjshade/grpc,wangyikai/grpc,jcanizales/grpc,grani/grpc,MakMukhi/grpc,bjori/grpc,dklempner/grpc,pszemus/grpc,soltanmm-google/grpc,geffzhang/grpc,PeterFaiman/ruby-grpc-minimal,jboeuf/grpc,carl-mastrangelo/grpc,pmarks-net/grpc,podsvirov/grpc,makdharma/grpc,7anner/grpc,kpayson64/grpc,philcleveland/grpc,dgquintas/grpc,nicolasnoble/grpc,thinkerou/grpc,pszemus/grpc,daniel-j-born/grpc,pszemus/grpc,msmania/grpc,firebase/grpc,LuminateWireless/grpc,dklempner/grpc,bjori/grpc,MakMukhi/grpc,yang-g/grpc,makdharma/grpc,firebase/grpc,zeliard/grpc,jcanizales/grpc,Vizerai/grpc,simonkuang/grpc,jcanizales/grpc,mehrdada/grpc,muxi/grpc,vsco/grpc,zeliard/grpc,larsonmpdx/grpc,rjshade/grpc,matt-kwong/grpc,kskalski/grpc,carl-mastrangelo/grpc,ejona86/grpc,yinsu/grpc,miselin/grpc,nicolasnoble/grpc,zhimingxie/grpc,doubi-workshop/grpc,rjshade/grpc,donnadionne/grpc,infinit/grpc,VcamX/grpc,geffzhang/grpc,grani/grpc,simonkuang/grpc,grpc/grpc,vjpai/grpc,cgvarela/grpc,adelez/grpc,kumaralokgithub/grpc,cgvarela/grpc,miselin/grpc,nicolasnoble/grpc,grani/grpc,vsco/grpc,carl-mastrangelo/grpc,wcevans/grpc,apolcyn/grpc,tamihiro/grpc,stanley-cheung/grpc,jboeuf/grpc,ofrobots/grpc,jtattermusch/grpc,nicolasnoble/grpc,cgvarela/grpc,pmarks-net/grpc,ofrobots/grpc,ejona86/grpc,soltanmm/grpc,thunderboltsid/grpc,wkubiak/grpc,vjpai/grpc,wcevans/grpc,yugui/grpc,ananthonline/grpc,yonglehou/grpc,wkubiak/grpc,soltanmm/grpc,crast/grpc,meisterpeeps/grpc,ncteisen/grpc,ncteisen/grpc,greasypizza/grpc,MakMukhi/grpc,msmania/grpc,andrewpollock/grpc,greasypizza/grpc,thunderboltsid/grpc,gpndata/grpc,nicolasnoble/grpc,thinkerou/grpc,doubi-workshop/grpc,fuchsia-mirror/third_party-grpc,carl-mastrangelo/grpc,y-zeng/grpc