Updated grpcio c extension build for windows to use mingw.
Updated grpcio c extension build for windows to use mingw.

The default compiler for Python c extensions is VS2008
or VS2010 depending on the Python version.  Since c-core
moved onto the c99 standard, these compilers are not
compatible.

nicolasnoble/grpc,yang-g/grpc,deepaklukose/grpc,Crevil/grpc,jboeuf/grpc,yugui/grpc,ctiller/grpc,jtattermusch/grpc,muxi/grpc,malexzx/grpc,ctiller/grpc,stanley-cheung/grpc,Vizerai/grpc,dklempner/grpc,ipylypiv/grpc,murgatroid99/grpc,makdharma/grpc,mehrdada/grpc,nicolasnoble/grpc,malexzx/grpc,y-zeng/grpc,grpc/grpc,royalharsh/grpc,donnadionne/grpc,greasypizza/grpc,simonkuang/grpc,ppietrasa/grpc,thunderboltsid/grpc,podsvirov/grpc,muxi/grpc,donnadionne/grpc,jtattermusch/grpc,sreecha/grpc,a-veitch/grpc,y-zeng/grpc,jboeuf/grpc,vjpai/grpc,vjpai/grpc,murgatroid99/grpc,rjshade/grpc,grani/grpc,zhimingxie/grpc,infinit/grpc,donnadionne/grpc,PeterFaiman/ruby-grpc-minimal,dklempner/grpc,geffzhang/grpc,carl-mastrangelo/grpc,dklempner/grpc,donnadionne/grpc,tengyifei/grpc,firebase/grpc,kriswuollett/grpc,baylabs/grpc,a-veitch/grpc,soltanmm/grpc,bogdandrutu/grpc,mehrdada/grpc,quizlet/grpc,daniel-j-born/grpc,zhimingxie/grpc,kumaralokgithub/grpc,Vizerai/grpc,ppietrasa/grpc,carl-mastrangelo/grpc,infinit/grpc,grpc/grpc,baylabs/grpc,dgquintas/grpc,soltanmm/grpc,greasypizza/grpc,vsco/grpc,zhimingxie/grpc,MakMukhi/grpc,grani/grpc,msmania/grpc,yugui/grpc,arkmaxim/grpc,PeterFaiman/ruby-grpc-minimal,apolcyn/grpc,baylabs/grpc,jtattermusch/grpc,ncteisen/grpc,a11r/grpc,rjshade/grpc,thinkerou/grpc,andrewpollock/grpc,fuchsia-mirror/third_party-grpc,jtattermusch/grpc,Crevil/grpc,philcleveland/grpc,arkmaxim/grpc,zhimingxie/grpc,dgquintas/grpc,mehrdada/grpc,wcevans/grpc,makdharma/grpc,firebase/grpc,malexzx/grpc,hstefan/grpc,pszemus/grpc,adelez/grpc,infinit/grpc,kpayson64/grpc,perumaalgoog/grpc,bogdandrutu/grpc,soltanmm/grpc,vjpai/grpc,carl-mastrangelo/grpc,andrewpollock/grpc,jtattermusch/grpc,soltanmm/grpc,deepaklukose/grpc,jcanizales/grpc,stanley-cheung/grpc,kskalski/grpc,fuchsia-mirror/third_party-grpc,ncteisen/grpc,muxi/grpc,malexzx/grpc,nicolasnoble/grpc,sreecha/grpc,y-zeng/grpc,msmania/grpc,zhimingxie/grpc,andrewpollock/grpc,zhimingxie/grpc,rjshade/grpc,perumaalgoog/grpc,donnadionne/grpc,pszemus/grpc,ipylypiv/grpc,podsvirov/grpc,hstefan/grpc,dgquintas/grpc,dklempner/grpc,malexzx/grpc,dgquintas/grpc,simonkuang/grpc,chrisdunelm/grpc,yugui/grpc,jboeuf/grpc,perumaalgoog/grpc,dgquintas/grpc,donnadionne/grpc,vjpai/grpc,thinkerou/grpc,Vizerai/grpc,jtattermusch/grpc,7anner/grpc,royalharsh/grpc,ipylypiv/grpc,soltanmm-google/grpc,firebase/grpc,ctiller/grpc,Crevil/grpc,stanley-cheung/grpc,kskalski/grpc,pmarks-net/grpc,kriswuollett/grpc,jcanizales/grpc,ctiller/grpc,fuchsia-mirror/third_party-grpc,daniel-j-born/grpc,hstefan/grpc,sreecha/grpc,adelez/grpc,royalharsh/grpc,podsvirov/grpc,stanley-cheung/grpc,mehrdada/grpc,geffzhang/grpc,mehrdada/grpc,yang-g/grpc,vjpai/grpc,arkmaxim/grpc,ctiller/grpc,greasypizza/grpc,yugui/grpc,vjpai/grpc,sreecha/grpc,kpayson64/grpc,y-zeng/grpc,MakMukhi/grpc,MakMukhi/grpc,a11r/grpc,jboeuf/grpc,andrewpollock/grpc,sreecha/grpc,yongni/grpc,grpc/grpc,thunderboltsid/grpc,geffzhang/grpc,geffzhang/grpc,kriswuollett/grpc,7anner/grpc,pszemus/grpc,y-zeng/grpc,soltanmm-google/grpc,thunderboltsid/grpc,sreecha/grpc,kumaralokgithub/grpc,yang-g/grpc,PeterFaiman/ruby-grpc-minimal,quizlet/grpc,royalharsh/grpc,geffzhang/grpc,Vizerai/grpc,mehrdada/grpc,kskalski/grpc,vjpai/grpc,hstefan/grpc,quizlet/grpc,jboeuf/grpc,pszemus/grpc,pszemus/grpc,stanley-cheung/grpc,thinkerou/grpc,LuminateWireless/grpc,deepaklukose/grpc,msmania/grpc,vjpai/grpc,daniel-j-born/grpc,Vizerai/grpc,msmania/grpc,Vizerai/grpc,donnadionne/grpc,firebase/grpc,chrisdunelm/grpc,perumaalgoog/grpc,LuminateWireless/grpc,ctiller/grpc,malexzx/grpc,LuminateWireless/grpc,nicolasnoble/grpc,tengyifei/grpc,yugui/grpc,jtattermusch/grpc,kpayson64/grpc,PeterFaiman/ruby-grpc-minimal,grpc/grpc,thunderboltsid/grpc,soltanmm/grpc,kriswuollett/grpc,kumaralokgithub/grpc,grani/grpc,soltanmm/grpc,ctiller/grpc,dgquintas/grpc,vsco/grpc,soltanmm-google/grpc,MakMukhi/grpc,kpayson64/grpc,y-zeng/grpc,pszemus/grpc,baylabs/grpc,ppietrasa/grpc,pszemus/grpc,ppietrasa/grpc,wcevans/grpc,bogdandrutu/grpc,nicolasnoble/grpc,podsvirov/grpc,jcanizales/grpc,grpc/grpc,arkmaxim/grpc,nicolasnoble/grpc,LuminateWireless/grpc,matt-kwong/grpc,donnadionne/grpc,perumaalgoog/grpc,grani/grpc,thinkerou/grpc,simonkuang/grpc,ejona86/grpc,infinit/grpc,philcleveland/grpc,apolcyn/grpc,baylabs/grpc,kriswuollett/grpc,grpc/grpc,PeterFaiman/ruby-grpc-minimal,apolcyn/grpc,sreecha/grpc,a11r/grpc,rjshade/grpc,perumaalgoog/grpc,dgquintas/grpc,yugui/grpc,royalharsh/grpc,Crevil/grpc,perumaalgoog/grpc,ipylypiv/grpc,fuchsia-mirror/third_party-grpc,ipylypiv/grpc,makdharma/grpc,wcevans/grpc,fuchsia-mirror/third_party-grpc,yongni/grpc,thinkerou/grpc,chrisdunelm/grpc,fuchsia-mirror/third_party-grpc,makdharma/grpc,yang-g/grpc,baylabs/grpc,dgquintas/grpc,pmarks-net/grpc,geffzhang/grpc,pmarks-net/grpc,yang-g/grpc,PeterFaiman/ruby-grpc-minimal,thunderboltsid/grpc,dklempner/grpc,daniel-j-born/grpc,kumaralokgithub/grpc,geffzhang/grpc,yongni/grpc,kpayson64/grpc,yang-g/grpc,muxi/grpc,podsvirov/grpc,pszemus/grpc,kskalski/grpc,kpayson64/grpc,kpayson64/grpc,fuchsia-mirror/third_party-grpc,nicolasnoble/grpc,tengyifei/grpc,nicolasnoble/grpc,vsco/grpc,muxi/grpc,jtattermusch/grpc,fuchsia-mirror/third_party-grpc,grpc/grpc,MakMukhi/grpc,jboeuf/grpc,greasypizza/grpc,deepaklukose/grpc,ejona86/grpc,tengyifei/grpc,apolcyn/grpc,donnadionne/grpc,firebase/grpc,hstefan/grpc,simonkuang/grpc,nicolasnoble/grpc,ejona86/grpc,grpc/grpc,muxi/grpc,7anner/grpc,ppietrasa/grpc,pmarks-net/grpc,ncteisen/grpc,7anner/grpc,Vizerai/grpc,jtattermusch/grpc,LuminateWireless/grpc,jcanizales/grpc,hstefan/grpc,LuminateWireless/grpc,bogdandrutu/grpc,jcanizales/grpc,hstefan/grpc,wcevans/grpc,chrisdunelm/grpc,pmarks-net/grpc,wcevans/grpc,y-zeng/grpc,a11r/grpc,ctiller/grpc,adelez/grpc,nicolasnoble/grpc,mehrdada/grpc,ejona86/grpc,andrewpollock/grpc,stanley-cheung/grpc,quizlet/grpc,stanley-cheung/grpc,greasypizza/grpc,dgquintas/grpc,kumaralokgithub/grpc,kumaralokgithub/grpc,thunderboltsid/grpc,pmarks-net/grpc,dklempner/grpc,murgatroid99/grpc,carl-mastrangelo/grpc,yugui/grpc,deepaklukose/grpc,muxi/grpc,dgquintas/grpc,LuminateWireless/grpc,pszemus/grpc,msmania/grpc,kskalski/grpc,jboeuf/grpc,7anner/grpc,ppietrasa/grpc,perumaalgoog/grpc,philcleveland/grpc,adelez/grpc,ejona86/grpc,MakMukhi/grpc,baylabs/grpc,soltanmm/grpc,andrewpollock/grpc,grpc/grpc,carl-mastrangelo/grpc,matt-kwong/grpc,daniel-j-born/grpc,vsco/grpc,thunderboltsid/grpc,vsco/grpc,yugui/grpc,grani/grpc,msmania/grpc,sreecha/grpc,carl-mastrangelo/grpc,malexzx/grpc,mehrdada/grpc,podsvirov/grpc,kriswuollett/grpc,murgatroid99/grpc,simonkuang/grpc,yang-g/grpc,greasypizza/grpc,simonkuang/grpc,podsvirov/grpc,nicolasnoble/grpc,andrewpollock/grpc,ejona86/grpc,simonkuang/grpc,makdharma/grpc,ipylypiv/grpc,pmarks-net/grpc,muxi/grpc,bogdandrutu/grpc,jtattermusch/grpc,tengyifei/grpc,kpayson64/grpc,donnadionne/grpc,a-veitch/grpc,pszemus/grpc,7anner/grpc,muxi/grpc,ncteisen/grpc,thinkerou/grpc,y-zeng/grpc,yongni/grpc,pmarks-net/grpc,a11r/grpc,sreecha/grpc,kskalski/grpc,stanley-cheung/grpc,deepaklukose/grpc,ncteisen/grpc,makdharma/grpc,nicolasnoble/grpc,kskalski/grpc,dklempner/grpc,bogdandrutu/grpc,firebase/grpc,wcevans/grpc,yongni/grpc,Crevil/grpc,vsco/grpc,deepaklukose/grpc,a-veitch/grpc,pmarks-net/grpc,firebase/grpc,podsvirov/grpc,wcevans/grpc,arkmaxim/grpc,quizlet/grpc,jcanizales/grpc,mehrdada/grpc,malexzx/grpc,kpayson64/grpc,apolcyn/grpc,deepaklukose/grpc,greasypizza/grpc,ncteisen/grpc,baylabs/grpc,ipylypiv/grpc,podsvirov/grpc,thinkerou/grpc,soltanmm-google/grpc,quizlet/grpc,arkmaxim/grpc,quizlet/grpc,a-veitch/grpc,chrisdunelm/grpc,adelez/grpc,a11r/grpc,philcleveland/grpc,perumaalgoog/grpc,grani/grpc,philcleveland/grpc,Crevil/grpc,ctiller/grpc,grani/grpc,wcevans/grpc,a11r/grpc,kumaralokgithub/grpc,hstefan/grpc,kskalski/grpc,ejona86/grpc,muxi/grpc,thinkerou/grpc,jboeuf/grpc,matt-kwong/grpc,ppietrasa/grpc,kriswuollett/grpc,apolcyn/grpc,ctiller/grpc,yongni/grpc,msmania/grpc,dgquintas/grpc,mehrdada/grpc,pszemus/grpc,adelez/grpc,rjshade/grpc,jcanizales/grpc,grani/grpc,wcevans/grpc,chrisdunelm/grpc,royalharsh/grpc,zhimingxie/grpc,ncteisen/grpc,geffzhang/grpc,Vizerai/grpc,soltanmm-google/grpc,soltanmm/grpc,grpc/grpc,geffzhang/grpc,dklempner/grpc,yongni/grpc,philcleveland/grpc,thunderboltsid/grpc,kskalski/grpc,infinit/grpc,dklempner/grpc,grani/grpc,PeterFaiman/ruby-grpc-minimal,carl-mastrangelo/grpc,Vizerai/grpc,matt-kwong/grpc,sreecha/grpc,Crevil/grpc,andrewpollock/grpc,carl-mastrangelo/grpc,quizlet/grpc,apolcyn/grpc,msmania/grpc,rjshade/grpc,infinit/grpc,ncteisen/grpc,tengyifei/grpc,msmania/grpc,kumaralokgithub/grpc,jboeuf/grpc,mehrdada/grpc,royalharsh/grpc,Crevil/grpc,jboeuf/grpc,MakMukhi/grpc,tengyifei/grpc,apolcyn/grpc,adelez/grpc,Vizerai/grpc,mehrdada/grpc,firebase/grpc,ctiller/grpc,y-zeng/grpc,LuminateWireless/grpc,ejona86/grpc,carl-mastrangelo/grpc,7anner/grpc,jboeuf/grpc,makdharma/grpc,adelez/grpc,fuchsia-mirror/third_party-grpc,bogdandrutu/grpc,simonkuang/grpc,yugui/grpc,daniel-j-born/grpc,thunderboltsid/grpc,matt-kwong/grpc,murgatroid99/grpc,soltanmm-google/grpc,Vizerai/grpc,rjshade/grpc,royalharsh/grpc,hstefan/grpc,grpc/grpc,PeterFaiman/ruby-grpc-minimal,a11r/grpc,vsco/grpc,ncteisen/grpc,stanley-cheung/grpc,muxi/grpc,vjpai/grpc,jboeuf/grpc,ncteisen/grpc,ipylypiv/grpc,LuminateWireless/grpc,daniel-j-born/grpc,murgatroid99/grpc,arkmaxim/grpc,apolcyn/grpc,donnadionne/grpc,arkmaxim/grpc,matt-kwong/grpc,carl-mastrangelo/grpc,malexzx/grpc,stanley-cheung/grpc,greasypizza/grpc,a-veitch/grpc,infinit/grpc,makdharma/grpc,kpayson64/grpc,murgatroid99/grpc,7anner/grpc,murgatroid99/grpc,jcanizales/grpc,firebase/grpc,rjshade/grpc,sreecha/grpc,zhimingxie/grpc,jtattermusch/grpc,a-veitch/grpc,kriswuollett/grpc,matt-kwong/grpc,philcleveland/grpc,vsco/grpc,chrisdunelm/grpc,andrewpollock/grpc,a-veitch/grpc,yang-g/grpc,matt-kwong/grpc,arkmaxim/grpc,soltanmm-google/grpc,kpayson64/grpc,ejona86/grpc,PeterFaiman/ruby-grpc-minimal,ipylypiv/grpc,simonkuang/grpc,kumaralokgithub/grpc,chrisdunelm/grpc,ppietrasa/grpc,a11r/grpc,ejona86/grpc,yang-g/grpc,deepaklukose/grpc,thinkerou/grpc,greasypizza/grpc,bogdandrutu/grpc,jtattermusch/grpc,soltanmm-google/grpc,MakMukhi/grpc,muxi/grpc,chrisdunelm/grpc,ctiller/grpc,chrisdunelm/grpc,vjpai/grpc,PeterFaiman/ruby-grpc-minimal,yongni/grpc,a-veitch/grpc,jcanizales/grpc,infinit/grpc,7anner/grpc,murgatroid99/grpc,adelez/grpc,philcleveland/grpc,ejona86/grpc,thinkerou/grpc,ncteisen/grpc,soltanmm-google/grpc,royalharsh/grpc,soltanmm/grpc,chrisdunelm/grpc,pszemus/grpc,grpc/grpc,sreecha/grpc,vsco/grpc,bogdandrutu/grpc,yongni/grpc,stanley-cheung/grpc,stanley-cheung/grpc,ppietrasa/grpc,zhimingxie/grpc,thinkerou/grpc,firebase/grpc,makdharma/grpc,kriswuollett/grpc,murgatroid99/grpc,carl-mastrangelo/grpc,firebase/grpc,daniel-j-born/grpc,Crevil/grpc,daniel-j-born/grpc,tengyifei/grpc,infinit/grpc,donnadionne/grpc,thinkerou/grpc,ejona86/grpc,MakMukhi/grpc,quizlet/grpc,carl-mastrangelo/grpc,matt-kwong/grpc,firebase/grpc,philcleveland/grpc,rjshade/grpc,vjpai/grpc,fuchsia-mirror/third_party-grpc,ncteisen/grpc,vjpai/grpc,tengyifei/grpc,baylabs/grpc