2x speedup for 'ant generate-immutables' by only running on subset of sources
2x speedup for 'ant generate-immutables' by only running on subset of sources

Summary:
When running the Java annotation processor to generate Immutables
classes on our codebase, we were previously running it on every file in the
codebase.

Turns out this is twice as slow as just grep'ing the codebase for
'org.immutables' and then running the annotation processor on those
files.

Test Plan:
Before:

  % time ant generate-immutables
  Buildfile: /Users/bgertzfield/devtools/buck/build.xml

  generate-immutables:
      [javac] Compiling 856 source files

  BUILD SUCCESSFUL
  Total time: 5 seconds
  ant generate-immutables  11.80s user 0.55s system 233% cpu 5.295 total

After:

  % time ant generate-immutables
  Buildfile: /Users/bgertzfield/devtools/buck/build.xml

  generate-immutables:
      [javac] Compiling 15 source files

  BUILD SUCCESSFUL
  Total time: 2 seconds
  ant generate-immutables  5.34s user 0.28s system 208% cpu 2.701 total

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