Make target graph hasing consisitent across platforms
Make target graph hasing consisitent across platforms

Summary:
Different slash characters for file paths means the hashes will be
different across platforms.  This makes it consistent.

Test Plan: `.\bin\buck test //test/com/facebook/buck/rules:rules`

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