UberRDotJava should cache the classes.txt file instead of the total hash.
UberRDotJava should cache the classes.txt file instead of the total hash.

Summary:
Because SplitZipStep will need access to this map to compute the hash of its
inputs. I was only focussed on PreDexMerge until my last diff, which packs an
entire DexWithClasses and so doesn't need to know the hash of individual classes.

Sorry for the churn, but I want to keep the diffs small, because threading this
all the way from class path entries to the smart dexing step is going to be a
big diff itself.

Test Plan:
buck test --all
sandcastle

justinmuller/buck,vine/buck,JoelMarcey/buck,vine/buck,darkforestzero/buck,shybovycha/buck,zhan-xiong/buck,illicitonion/buck,marcinkwiatkowski/buck,SeleniumHQ/buck,marcinkwiatkowski/buck,davido/buck,Heart2009/buck,neonichu/buck,liuyang-li/buck,Dominator008/buck,davido/buck,zhuxiaohao/buck,siddhartharay007/buck,lukw00/buck,Learn-Android-app/buck,rhencke/buck,vschs007/buck,rmaz/buck,Distrotech/buck,rowillia/buck,facebook/buck,liuyang-li/buck,mread/buck,justinmuller/buck,pwz3n0/buck,dsyang/buck,raviagarwal7/buck,LegNeato/buck,robbertvanginkel/buck,OkBuilds/buck,clonetwin26/buck,rmaz/buck,siddhartharay007/buck,tgummerer/buck,zhan-xiong/buck,janicduplessis/buck,MarkRunWu/buck,1yvT0s/buck,nguyentruongtho/buck,shybovycha/buck,robbertvanginkel/buck,sdwilsh/buck,janicduplessis/buck,romanoid/buck,illicitonion/buck,mnuessler/buck,saleeh93/buck-cutom,rhencke/buck,janicduplessis/buck,artiya4u/buck,OkBuilds/buck,pwz3n0/buck,justinmuller/buck,zhuxiaohao/buck,Distrotech/buck,mikekap/buck,Dominator008/buck,artiya4u/buck,darkforestzero/buck,clonetwin26/buck,dsyang/buck,dushmis/buck,k21/buck,Distrotech/buck,neonichu/buck,janicduplessis/buck,rmaz/buck,mogers/buck,1yvT0s/buck,zhuxiaohao/buck,shs96c/buck,siddhartharay007/buck,Heart2009/buck,rowillia/buck,lukw00/buck,JoelMarcey/buck,robbertvanginkel/buck,hgl888/buck,saleeh93/buck-cutom,mogers/buck,justinmuller/buck,vine/buck,rmaz/buck,mogers/buck,stuhood/buck,rhencke/buck,LegNeato/buck,grumpyjames/buck,justinmuller/buck,LegNeato/buck,vschs007/buck,k21/buck,Dominator008/buck,raviagarwal7/buck,robbertvanginkel/buck,daedric/buck,rhencke/buck,daedric/buck,zpao/buck,OkBuilds/buck,davido/buck,JoelMarcey/buck,Dominator008/buck,raviagarwal7/buck,Heart2009/buck,stuhood/buck,kageiit/buck,saleeh93/buck-cutom,saleeh93/buck-cutom,janicduplessis/buck,MarkRunWu/buck,LegNeato/buck,Distrotech/buck,raviagarwal7/buck,davido/buck,clonetwin26/buck,rmaz/buck,sdwilsh/buck,Addepar/buck,bocon13/buck,ilya-klyuchnikov/buck,romanoid/buck,justinmuller/buck,facebook/buck,marcinkwiatkowski/buck,vschs007/buck,mnuessler/buck,Addepar/buck,facebook/buck,pwz3n0/buck,ilya-klyuchnikov/buck,zhuxiaohao/buck,OkBuilds/buck,Addepar/buck,siddhartharay007/buck,robbertvanginkel/buck,mikekap/buck,lukw00/buck,janicduplessis/buck,hgl888/buck,darkforestzero/buck,mnuessler/buck,pwz3n0/buck,shs96c/buck,JoelMarcey/buck,darkforestzero/buck,1yvT0s/buck,dushmis/buck,nguyentruongtho/buck,dsyang/buck,davido/buck,Distrotech/buck,lukw00/buck,grumpyjames/buck,pwz3n0/buck,shs96c/buck,mikekap/buck,dpursehouse/buck,mread/buck,vschs007/buck,grumpyjames/buck,illicitonion/buck,daedric/buck,mnuessler/buck,liuyang-li/buck,clonetwin26/buck,darkforestzero/buck,ilya-klyuchnikov/buck,1yvT0s/buck,siddhartharay007/buck,k21/buck,dsyang/buck,Learn-Android-app/buck,romanoid/buck,tgummerer/buck,rmaz/buck,raviagarwal7/buck,JoelMarcey/buck,bocon13/buck,facebook/buck,artiya4u/buck,dsyang/buck,justinmuller/buck,SeleniumHQ/buck,k21/buck,stuhood/buck,robbertvanginkel/buck,bocon13/buck,Learn-Android-app/buck,Addepar/buck,zhuxiaohao/buck,shs96c/buck,daedric/buck,SeleniumHQ/buck,artiya4u/buck,ilya-klyuchnikov/buck,mread/buck,marcinkwiatkowski/buck,Heart2009/buck,darkforestzero/buck,rmaz/buck,zhan-xiong/buck,janicduplessis/buck,pwz3n0/buck,sdwilsh/buck,LegNeato/buck,tgummerer/buck,lukw00/buck,OkBuilds/buck,mikekap/buck,kageiit/buck,k21/buck,ilya-klyuchnikov/buck,Distrotech/buck,mikekap/buck,Dominator008/buck,Addepar/buck,Addepar/buck,shs96c/buck,mikekap/buck,romanoid/buck,kageiit/buck,darkforestzero/buck,sdwilsh/buck,grumpyjames/buck,mikekap/buck,raviagarwal7/buck,Addepar/buck,rhencke/buck,illicitonion/buck,zhan-xiong/buck,lukw00/buck,pwz3n0/buck,davido/buck,clonetwin26/buck,nguyentruongtho/buck,mread/buck,pwz3n0/buck,luiseduardohdbackup/buck,Learn-Android-app/buck,raviagarwal7/buck,clonetwin26/buck,janicduplessis/buck,grumpyjames/buck,dushmis/buck,shs96c/buck,mread/buck,liuyang-li/buck,zhuxiaohao/buck,vschs007/buck,romanoid/buck,Dominator008/buck,stuhood/buck,SeleniumHQ/buck,SeleniumHQ/buck,nguyentruongtho/buck,raviagarwal7/buck,sdwilsh/buck,vschs007/buck,OkBuilds/buck,sdwilsh/buck,dushmis/buck,robbertvanginkel/buck,illicitonion/buck,shs96c/buck,Heart2009/buck,OkBuilds/buck,bocon13/buck,luiseduardohdbackup/buck,LegNeato/buck,marcinkwiatkowski/buck,liuyang-li/buck,tgummerer/buck,clonetwin26/buck,tgummerer/buck,mogers/buck,vschs007/buck,JoelMarcey/buck,sdwilsh/buck,sdwilsh/buck,pwz3n0/buck,dushmis/buck,shybovycha/buck,brettwooldridge/buck,shybovycha/buck,dpursehouse/buck,mogers/buck,mikekap/buck,marcinkwiatkowski/buck,facebook/buck,ilya-klyuchnikov/buck,stuhood/buck,bocon13/buck,clonetwin26/buck,brettwooldridge/buck,LegNeato/buck,nguyentruongtho/buck,1yvT0s/buck,ilya-klyuchnikov/buck,hgl888/buck,OkBuilds/buck,Heart2009/buck,dpursehouse/buck,kageiit/buck,zhan-xiong/buck,lukw00/buck,marcinkwiatkowski/buck,stuhood/buck,justinmuller/buck,artiya4u/buck,sdwilsh/buck,vschs007/buck,Learn-Android-app/buck,shybovycha/buck,1yvT0s/buck,neonichu/buck,hgl888/buck,Addepar/buck,Distrotech/buck,sdwilsh/buck,zpao/buck,artiya4u/buck,tgummerer/buck,vschs007/buck,zhan-xiong/buck,clonetwin26/buck,Addepar/buck,stuhood/buck,saleeh93/buck-cutom,lukw00/buck,clonetwin26/buck,grumpyjames/buck,shybovycha/buck,Distrotech/buck,k21/buck,daedric/buck,neonichu/buck,liuyang-li/buck,robbertvanginkel/buck,shybovycha/buck,mogers/buck,SeleniumHQ/buck,ilya-klyuchnikov/buck,davido/buck,Heart2009/buck,1yvT0s/buck,JoelMarcey/buck,illicitonion/buck,dsyang/buck,robbertvanginkel/buck,shs96c/buck,justinmuller/buck,SeleniumHQ/buck,rowillia/buck,illicitonion/buck,dpursehouse/buck,rowillia/buck,tgummerer/buck,Dominator008/buck,MarkRunWu/buck,OkBuilds/buck,neonichu/buck,justinmuller/buck,liuyang-li/buck,saleeh93/buck-cutom,LegNeato/buck,mogers/buck,artiya4u/buck,Learn-Android-app/buck,romanoid/buck,zhan-xiong/buck,daedric/buck,vine/buck,shs96c/buck,zhan-xiong/buck,pwz3n0/buck,rmaz/buck,dushmis/buck,vine/buck,ilya-klyuchnikov/buck,sdwilsh/buck,JoelMarcey/buck,rhencke/buck,darkforestzero/buck,rhencke/buck,illicitonion/buck,dpursehouse/buck,zpao/buck,tgummerer/buck,illicitonion/buck,vine/buck,JoelMarcey/buck,LegNeato/buck,SeleniumHQ/buck,raviagarwal7/buck,mikekap/buck,dushmis/buck,marcinkwiatkowski/buck,artiya4u/buck,grumpyjames/buck,dpursehouse/buck,robbertvanginkel/buck,rowillia/buck,darkforestzero/buck,darkforestzero/buck,davido/buck,mogers/buck,mnuessler/buck,raviagarwal7/buck,brettwooldridge/buck,siddhartharay007/buck,janicduplessis/buck,facebook/buck,MarkRunWu/buck,zhuxiaohao/buck,rmaz/buck,mikekap/buck,zhan-xiong/buck,illicitonion/buck,SeleniumHQ/buck,davido/buck,rowillia/buck,lukw00/buck,luiseduardohdbackup/buck,liuyang-li/buck,OkBuilds/buck,rowillia/buck,mikekap/buck,kageiit/buck,daedric/buck,illicitonion/buck,dushmis/buck,JoelMarcey/buck,nguyentruongtho/buck,MarkRunWu/buck,dsyang/buck,OkBuilds/buck,k21/buck,dsyang/buck,neonichu/buck,zpao/buck,mnuessler/buck,shybovycha/buck,rhencke/buck,stuhood/buck,marcinkwiatkowski/buck,clonetwin26/buck,clonetwin26/buck,kageiit/buck,SeleniumHQ/buck,sdwilsh/buck,vschs007/buck,LegNeato/buck,LegNeato/buck,dsyang/buck,k21/buck,stuhood/buck,davido/buck,Learn-Android-app/buck,artiya4u/buck,Dominator008/buck,zhan-xiong/buck,brettwooldridge/buck,JoelMarcey/buck,daedric/buck,vschs007/buck,shs96c/buck,romanoid/buck,hgl888/buck,facebook/buck,darkforestzero/buck,dsyang/buck,zhan-xiong/buck,romanoid/buck,zhan-xiong/buck,rmaz/buck,1yvT0s/buck,luiseduardohdbackup/buck,OkBuilds/buck,brettwooldridge/buck,neonichu/buck,davido/buck,SeleniumHQ/buck,1yvT0s/buck,lukw00/buck,shs96c/buck,dsyang/buck,grumpyjames/buck,vine/buck,grumpyjames/buck,bocon13/buck,janicduplessis/buck,bocon13/buck,k21/buck,brettwooldridge/buck,rhencke/buck,MarkRunWu/buck,vschs007/buck,shybovycha/buck,SeleniumHQ/buck,clonetwin26/buck,shybovycha/buck,justinmuller/buck,k21/buck,davido/buck,siddhartharay007/buck,rhencke/buck,vine/buck,brettwooldridge/buck,dpursehouse/buck,hgl888/buck,daedric/buck,luiseduardohdbackup/buck,robbertvanginkel/buck,mnuessler/buck,mogers/buck,shybovycha/buck,rmaz/buck,mread/buck,JoelMarcey/buck,zhuxiaohao/buck,shs96c/buck,brettwooldridge/buck,vschs007/buck,bocon13/buck,mogers/buck,grumpyjames/buck,romanoid/buck,liuyang-li/buck,zpao/buck,ilya-klyuchnikov/buck,rowillia/buck,daedric/buck,Dominator008/buck,siddhartharay007/buck,Learn-Android-app/buck,artiya4u/buck,rowillia/buck,k21/buck,neonichu/buck,ilya-klyuchnikov/buck,stuhood/buck,janicduplessis/buck,Addepar/buck,luiseduardohdbackup/buck,Distrotech/buck,dpursehouse/buck,Dominator008/buck,hgl888/buck,marcinkwiatkowski/buck,robbertvanginkel/buck,Addepar/buck,romanoid/buck,bocon13/buck,Distrotech/buck,marcinkwiatkowski/buck,shs96c/buck,romanoid/buck,MarkRunWu/buck,hgl888/buck,robbertvanginkel/buck,mikekap/buck,MarkRunWu/buck,luiseduardohdbackup/buck,k21/buck,zpao/buck,Learn-Android-app/buck,rmaz/buck,shybovycha/buck,lukw00/buck,illicitonion/buck,Learn-Android-app/buck,stuhood/buck,k21/buck,LegNeato/buck,dushmis/buck,mnuessler/buck,romanoid/buck,nguyentruongtho/buck,rowillia/buck,justinmuller/buck,bocon13/buck,romanoid/buck,janicduplessis/buck,illicitonion/buck,Learn-Android-app/buck,daedric/buck,rhencke/buck,zhuxiaohao/buck,ilya-klyuchnikov/buck,Addepar/buck,liuyang-li/buck,raviagarwal7/buck,LegNeato/buck,brettwooldridge/buck,darkforestzero/buck,sdwilsh/buck,mogers/buck,Addepar/buck,rmaz/buck,brettwooldridge/buck,ilya-klyuchnikov/buck,daedric/buck,JoelMarcey/buck,SeleniumHQ/buck,dsyang/buck,dsyang/buck,shybovycha/buck,tgummerer/buck,raviagarwal7/buck,artiya4u/buck,Heart2009/buck,zhan-xiong/buck,siddhartharay007/buck,Distrotech/buck,brettwooldridge/buck,liuyang-li/buck,rowillia/buck,tgummerer/buck,vine/buck,daedric/buck,raviagarwal7/buck,darkforestzero/buck,bocon13/buck,hgl888/buck,vine/buck,luiseduardohdbackup/buck,Dominator008/buck,neonichu/buck,Dominator008/buck,pwz3n0/buck,mnuessler/buck,zpao/buck,grumpyjames/buck,justinmuller/buck,Heart2009/buck,luiseduardohdbackup/buck,dushmis/buck,brettwooldridge/buck,OkBuilds/buck,vine/buck,davido/buck,tgummerer/buck,kageiit/buck,marcinkwiatkowski/buck,marcinkwiatkowski/buck,rowillia/buck,grumpyjames/buck,brettwooldridge/buck,bocon13/buck