Treat empty files as non-existing in the launcher scripts.
Treat empty files as non-existing in the launcher scripts.

Summary: I thought this was better than modifying all the call sites to do this check.

Test Plan:
```
$ buckd
$ echo "" > .buckd/buckd.runcount
$ buck
```

brettwooldridge/buck,rowillia/buck,stuhood/buck,illicitonion/buck,davido/buck,MarkRunWu/buck,dpursehouse/buck,daedric/buck,mogers/buck,siddhartharay007/buck,dsyang/buck,bocon13/buck,Distrotech/buck,marcinkwiatkowski/buck,rmaz/buck,Addepar/buck,mikekap/buck,dushmis/buck,artiya4u/buck,SeleniumHQ/buck,JoelMarcey/buck,davido/buck,siddhartharay007/buck,rhencke/buck,clonetwin26/buck,Learn-Android-app/buck,darkforestzero/buck,MarkRunWu/buck,ilya-klyuchnikov/buck,daedric/buck,grumpyjames/buck,zhan-xiong/buck,rhencke/buck,Addepar/buck,neonichu/buck,siddhartharay007/buck,k21/buck,brettwooldridge/buck,luiseduardohdbackup/buck,daedric/buck,siddhartharay007/buck,JoelMarcey/buck,neonichu/buck,illicitonion/buck,zpao/buck,marcinkwiatkowski/buck,clonetwin26/buck,darkforestzero/buck,OkBuilds/buck,robbertvanginkel/buck,marcinkwiatkowski/buck,rmaz/buck,1yvT0s/buck,Addepar/buck,rowillia/buck,pwz3n0/buck,JoelMarcey/buck,robbertvanginkel/buck,artiya4u/buck,daedric/buck,davido/buck,shybovycha/buck,k21/buck,zhan-xiong/buck,justinmuller/buck,janicduplessis/buck,shs96c/buck,illicitonion/buck,Heart2009/buck,vschs007/buck,davido/buck,brettwooldridge/buck,marcinkwiatkowski/buck,rhencke/buck,robbertvanginkel/buck,grumpyjames/buck,tgummerer/buck,Distrotech/buck,ilya-klyuchnikov/buck,dsyang/buck,grumpyjames/buck,Addepar/buck,rowillia/buck,mnuessler/buck,mikekap/buck,neonichu/buck,zhan-xiong/buck,1yvT0s/buck,daedric/buck,grumpyjames/buck,hgl888/buck,shybovycha/buck,LegNeato/buck,bocon13/buck,vine/buck,neonichu/buck,brettwooldridge/buck,nguyentruongtho/buck,SeleniumHQ/buck,tgummerer/buck,janicduplessis/buck,SeleniumHQ/buck,lukw00/buck,Heart2009/buck,siddhartharay007/buck,SeleniumHQ/buck,zhan-xiong/buck,vschs007/buck,Learn-Android-app/buck,dushmis/buck,lukw00/buck,LegNeato/buck,hgl888/buck,rmaz/buck,lukw00/buck,zhuxiaohao/buck,Learn-Android-app/buck,vine/buck,bocon13/buck,clonetwin26/buck,pwz3n0/buck,mogers/buck,vschs007/buck,vschs007/buck,vschs007/buck,justinmuller/buck,vine/buck,ilya-klyuchnikov/buck,siddhartharay007/buck,rmaz/buck,shs96c/buck,shybovycha/buck,mogers/buck,davido/buck,sdwilsh/buck,robbertvanginkel/buck,rhencke/buck,kageiit/buck,JoelMarcey/buck,shybovycha/buck,robbertvanginkel/buck,rhencke/buck,justinmuller/buck,Distrotech/buck,davido/buck,mogers/buck,mikekap/buck,justinmuller/buck,mikekap/buck,Heart2009/buck,justinmuller/buck,JoelMarcey/buck,raviagarwal7/buck,k21/buck,mnuessler/buck,JoelMarcey/buck,grumpyjames/buck,janicduplessis/buck,LegNeato/buck,neonichu/buck,raviagarwal7/buck,darkforestzero/buck,illicitonion/buck,sdwilsh/buck,brettwooldridge/buck,clonetwin26/buck,lukw00/buck,artiya4u/buck,davido/buck,MarkRunWu/buck,Addepar/buck,zhuxiaohao/buck,LegNeato/buck,Learn-Android-app/buck,rmaz/buck,vine/buck,rmaz/buck,vschs007/buck,mikekap/buck,romanoid/buck,bocon13/buck,raviagarwal7/buck,neonichu/buck,mogers/buck,rowillia/buck,janicduplessis/buck,zhan-xiong/buck,clonetwin26/buck,neonichu/buck,OkBuilds/buck,mnuessler/buck,zpao/buck,mread/buck,k21/buck,shybovycha/buck,tgummerer/buck,kageiit/buck,shybovycha/buck,tgummerer/buck,1yvT0s/buck,SeleniumHQ/buck,daedric/buck,romanoid/buck,facebook/buck,vine/buck,facebook/buck,pwz3n0/buck,marcinkwiatkowski/buck,tgummerer/buck,dpursehouse/buck,darkforestzero/buck,dsyang/buck,justinmuller/buck,darkforestzero/buck,k21/buck,janicduplessis/buck,raviagarwal7/buck,OkBuilds/buck,Learn-Android-app/buck,liuyang-li/buck,Dominator008/buck,bocon13/buck,OkBuilds/buck,clonetwin26/buck,lukw00/buck,JoelMarcey/buck,clonetwin26/buck,marcinkwiatkowski/buck,darkforestzero/buck,rowillia/buck,Heart2009/buck,shybovycha/buck,mnuessler/buck,grumpyjames/buck,luiseduardohdbackup/buck,clonetwin26/buck,illicitonion/buck,hgl888/buck,Dominator008/buck,romanoid/buck,Distrotech/buck,rmaz/buck,robbertvanginkel/buck,ilya-klyuchnikov/buck,vine/buck,SeleniumHQ/buck,mogers/buck,sdwilsh/buck,k21/buck,liuyang-li/buck,MarkRunWu/buck,romanoid/buck,vine/buck,shs96c/buck,vschs007/buck,ilya-klyuchnikov/buck,dpursehouse/buck,brettwooldridge/buck,kageiit/buck,dsyang/buck,Dominator008/buck,sdwilsh/buck,SeleniumHQ/buck,raviagarwal7/buck,mread/buck,mikekap/buck,mikekap/buck,tgummerer/buck,shs96c/buck,lukw00/buck,ilya-klyuchnikov/buck,darkforestzero/buck,grumpyjames/buck,tgummerer/buck,daedric/buck,pwz3n0/buck,OkBuilds/buck,dushmis/buck,dpursehouse/buck,mogers/buck,dushmis/buck,shs96c/buck,hgl888/buck,rhencke/buck,LegNeato/buck,shs96c/buck,dsyang/buck,OkBuilds/buck,mread/buck,Learn-Android-app/buck,janicduplessis/buck,romanoid/buck,dushmis/buck,marcinkwiatkowski/buck,artiya4u/buck,mnuessler/buck,stuhood/buck,shybovycha/buck,rowillia/buck,robbertvanginkel/buck,illicitonion/buck,pwz3n0/buck,vschs007/buck,liuyang-li/buck,lukw00/buck,bocon13/buck,Dominator008/buck,Heart2009/buck,luiseduardohdbackup/buck,Addepar/buck,janicduplessis/buck,luiseduardohdbackup/buck,Learn-Android-app/buck,dpursehouse/buck,bocon13/buck,pwz3n0/buck,raviagarwal7/buck,raviagarwal7/buck,ilya-klyuchnikov/buck,davido/buck,daedric/buck,tgummerer/buck,Heart2009/buck,MarkRunWu/buck,justinmuller/buck,liuyang-li/buck,ilya-klyuchnikov/buck,tgummerer/buck,Addepar/buck,raviagarwal7/buck,JoelMarcey/buck,darkforestzero/buck,Dominator008/buck,siddhartharay007/buck,zpao/buck,darkforestzero/buck,1yvT0s/buck,LegNeato/buck,brettwooldridge/buck,dsyang/buck,rhencke/buck,LegNeato/buck,robbertvanginkel/buck,davido/buck,zhan-xiong/buck,marcinkwiatkowski/buck,raviagarwal7/buck,dsyang/buck,artiya4u/buck,hgl888/buck,LegNeato/buck,OkBuilds/buck,daedric/buck,SeleniumHQ/buck,rmaz/buck,luiseduardohdbackup/buck,liuyang-li/buck,nguyentruongtho/buck,hgl888/buck,rowillia/buck,nguyentruongtho/buck,SeleniumHQ/buck,Dominator008/buck,sdwilsh/buck,Distrotech/buck,rowillia/buck,clonetwin26/buck,mread/buck,sdwilsh/buck,SeleniumHQ/buck,stuhood/buck,grumpyjames/buck,daedric/buck,1yvT0s/buck,marcinkwiatkowski/buck,k21/buck,kageiit/buck,grumpyjames/buck,vschs007/buck,sdwilsh/buck,romanoid/buck,pwz3n0/buck,1yvT0s/buck,brettwooldridge/buck,dsyang/buck,dushmis/buck,ilya-klyuchnikov/buck,pwz3n0/buck,neonichu/buck,grumpyjames/buck,Learn-Android-app/buck,1yvT0s/buck,rhencke/buck,shs96c/buck,vschs007/buck,rmaz/buck,rhencke/buck,zhuxiaohao/buck,robbertvanginkel/buck,Distrotech/buck,liuyang-li/buck,pwz3n0/buck,hgl888/buck,MarkRunWu/buck,romanoid/buck,LegNeato/buck,romanoid/buck,zpao/buck,Dominator008/buck,marcinkwiatkowski/buck,mogers/buck,zhan-xiong/buck,davido/buck,OkBuilds/buck,Addepar/buck,pwz3n0/buck,robbertvanginkel/buck,ilya-klyuchnikov/buck,vschs007/buck,luiseduardohdbackup/buck,facebook/buck,zpao/buck,Distrotech/buck,dsyang/buck,vine/buck,shybovycha/buck,rhencke/buck,tgummerer/buck,nguyentruongtho/buck,stuhood/buck,mogers/buck,sdwilsh/buck,marcinkwiatkowski/buck,liuyang-li/buck,shs96c/buck,Heart2009/buck,JoelMarcey/buck,mnuessler/buck,zhuxiaohao/buck,lukw00/buck,romanoid/buck,dsyang/buck,sdwilsh/buck,rmaz/buck,shybovycha/buck,SeleniumHQ/buck,zhuxiaohao/buck,raviagarwal7/buck,hgl888/buck,illicitonion/buck,Dominator008/buck,clonetwin26/buck,dsyang/buck,k21/buck,LegNeato/buck,davido/buck,MarkRunWu/buck,shs96c/buck,justinmuller/buck,robbertvanginkel/buck,JoelMarcey/buck,davido/buck,darkforestzero/buck,bocon13/buck,liuyang-li/buck,romanoid/buck,zhan-xiong/buck,romanoid/buck,daedric/buck,dpursehouse/buck,shs96c/buck,shs96c/buck,pwz3n0/buck,OkBuilds/buck,rhencke/buck,lukw00/buck,dsyang/buck,dushmis/buck,rowillia/buck,Addepar/buck,lukw00/buck,artiya4u/buck,mogers/buck,sdwilsh/buck,dushmis/buck,kageiit/buck,k21/buck,janicduplessis/buck,nguyentruongtho/buck,hgl888/buck,justinmuller/buck,k21/buck,daedric/buck,vschs007/buck,vine/buck,davido/buck,OkBuilds/buck,dushmis/buck,mread/buck,sdwilsh/buck,bocon13/buck,mikekap/buck,luiseduardohdbackup/buck,justinmuller/buck,romanoid/buck,stuhood/buck,brettwooldridge/buck,Dominator008/buck,illicitonion/buck,mnuessler/buck,illicitonion/buck,zhan-xiong/buck,artiya4u/buck,facebook/buck,shybovycha/buck,shybovycha/buck,Learn-Android-app/buck,siddhartharay007/buck,siddhartharay007/buck,Addepar/buck,LegNeato/buck,stuhood/buck,zhuxiaohao/buck,stuhood/buck,justinmuller/buck,daedric/buck,sdwilsh/buck,clonetwin26/buck,zhan-xiong/buck,facebook/buck,Distrotech/buck,dushmis/buck,vine/buck,artiya4u/buck,Dominator008/buck,stuhood/buck,clonetwin26/buck,stuhood/buck,marcinkwiatkowski/buck,ilya-klyuchnikov/buck,rmaz/buck,darkforestzero/buck,Learn-Android-app/buck,LegNeato/buck,vschs007/buck,mikekap/buck,Heart2009/buck,bocon13/buck,OkBuilds/buck,darkforestzero/buck,Addepar/buck,marcinkwiatkowski/buck,darkforestzero/buck,shs96c/buck,ilya-klyuchnikov/buck,robbertvanginkel/buck,mread/buck,Dominator008/buck,Learn-Android-app/buck,liuyang-li/buck,mogers/buck,illicitonion/buck,Distrotech/buck,raviagarwal7/buck,ilya-klyuchnikov/buck,sdwilsh/buck,JoelMarcey/buck,zpao/buck,k21/buck,zhuxiaohao/buck,shs96c/buck,LegNeato/buck,facebook/buck,SeleniumHQ/buck,vine/buck,liuyang-li/buck,artiya4u/buck,bocon13/buck,Distrotech/buck,k21/buck,luiseduardohdbackup/buck,dsyang/buck,MarkRunWu/buck,nguyentruongtho/buck,kageiit/buck,Dominator008/buck,rmaz/buck,mikekap/buck,shybovycha/buck,1yvT0s/buck,lukw00/buck,dpursehouse/buck,rmaz/buck,luiseduardohdbackup/buck,JoelMarcey/buck,rowillia/buck,rowillia/buck,illicitonion/buck,JoelMarcey/buck,zhan-xiong/buck,OkBuilds/buck,mnuessler/buck,zhuxiaohao/buck,stuhood/buck,justinmuller/buck,facebook/buck,OkBuilds/buck,raviagarwal7/buck,Heart2009/buck,rowillia/buck,nguyentruongtho/buck,tgummerer/buck,janicduplessis/buck,k21/buck,zpao/buck,brettwooldridge/buck,mikekap/buck,justinmuller/buck,Addepar/buck,dpursehouse/buck,Distrotech/buck,stuhood/buck,illicitonion/buck,brettwooldridge/buck,artiya4u/buck,robbertvanginkel/buck,grumpyjames/buck,neonichu/buck,romanoid/buck,zhan-xiong/buck,mikekap/buck,grumpyjames/buck,brettwooldridge/buck,Addepar/buck,clonetwin26/buck,raviagarwal7/buck,SeleniumHQ/buck,1yvT0s/buck,janicduplessis/buck,kageiit/buck,zhuxiaohao/buck,illicitonion/buck,zhan-xiong/buck,bocon13/buck,liuyang-li/buck,janicduplessis/buck,janicduplessis/buck,brettwooldridge/buck,artiya4u/buck,mnuessler/buck