Artificial project: android library does not always have output
Artificial project: android library does not always have output

Summary:
Like java libraries, android libraries don't have output unless
they have at least one source file. This change causes both to be
treated the same so they are not used as source paths in other
targets.

Test Plan:
Run the script and confirm it works with
`buck targets --show-rulekey`.

Reviewed By: Coneko

fbshipit-source-id: 7186b55

darkforestzero/buck,dsyang/buck,OkBuilds/buck,SeleniumHQ/buck,shs96c/buck,robbertvanginkel/buck,OkBuilds/buck,vschs007/buck,zhan-xiong/buck,k21/buck,rmaz/buck,shs96c/buck,ilya-klyuchnikov/buck,facebook/buck,OkBuilds/buck,dsyang/buck,dsyang/buck,k21/buck,shybovycha/buck,facebook/buck,OkBuilds/buck,romanoid/buck,shybovycha/buck,illicitonion/buck,ilya-klyuchnikov/buck,robbertvanginkel/buck,justinmuller/buck,raviagarwal7/buck,LegNeato/buck,clonetwin26/buck,ilya-klyuchnikov/buck,rmaz/buck,kageiit/buck,daedric/buck,nguyentruongtho/buck,Addepar/buck,JoelMarcey/buck,facebook/buck,rmaz/buck,sdwilsh/buck,ilya-klyuchnikov/buck,dsyang/buck,robbertvanginkel/buck,ilya-klyuchnikov/buck,brettwooldridge/buck,illicitonion/buck,daedric/buck,grumpyjames/buck,k21/buck,Addepar/buck,raviagarwal7/buck,k21/buck,shybovycha/buck,vschs007/buck,SeleniumHQ/buck,rmaz/buck,kageiit/buck,raviagarwal7/buck,zhan-xiong/buck,zhan-xiong/buck,zhan-xiong/buck,illicitonion/buck,shs96c/buck,facebook/buck,robbertvanginkel/buck,marcinkwiatkowski/buck,vschs007/buck,LegNeato/buck,SeleniumHQ/buck,darkforestzero/buck,zhan-xiong/buck,ilya-klyuchnikov/buck,brettwooldridge/buck,davido/buck,justinmuller/buck,marcinkwiatkowski/buck,dsyang/buck,sdwilsh/buck,marcinkwiatkowski/buck,sdwilsh/buck,marcinkwiatkowski/buck,sdwilsh/buck,JoelMarcey/buck,rmaz/buck,rmaz/buck,SeleniumHQ/buck,marcinkwiatkowski/buck,brettwooldridge/buck,Addepar/buck,shs96c/buck,romanoid/buck,zpao/buck,zpao/buck,justinmuller/buck,JoelMarcey/buck,vschs007/buck,illicitonion/buck,Addepar/buck,zpao/buck,zpao/buck,marcinkwiatkowski/buck,shybovycha/buck,kageiit/buck,JoelMarcey/buck,raviagarwal7/buck,vschs007/buck,justinmuller/buck,clonetwin26/buck,nguyentruongtho/buck,darkforestzero/buck,justinmuller/buck,darkforestzero/buck,zhan-xiong/buck,sdwilsh/buck,rmaz/buck,shybovycha/buck,LegNeato/buck,justinmuller/buck,darkforestzero/buck,shs96c/buck,brettwooldridge/buck,ilya-klyuchnikov/buck,Addepar/buck,JoelMarcey/buck,Addepar/buck,SeleniumHQ/buck,vschs007/buck,davido/buck,raviagarwal7/buck,LegNeato/buck,darkforestzero/buck,zhan-xiong/buck,nguyentruongtho/buck,SeleniumHQ/buck,clonetwin26/buck,OkBuilds/buck,romanoid/buck,Addepar/buck,shybovycha/buck,justinmuller/buck,darkforestzero/buck,OkBuilds/buck,facebook/buck,robbertvanginkel/buck,k21/buck,robbertvanginkel/buck,clonetwin26/buck,justinmuller/buck,darkforestzero/buck,zhan-xiong/buck,rmaz/buck,illicitonion/buck,shybovycha/buck,nguyentruongtho/buck,grumpyjames/buck,OkBuilds/buck,illicitonion/buck,daedric/buck,Addepar/buck,romanoid/buck,vschs007/buck,clonetwin26/buck,vschs007/buck,shs96c/buck,grumpyjames/buck,darkforestzero/buck,raviagarwal7/buck,daedric/buck,JoelMarcey/buck,LegNeato/buck,marcinkwiatkowski/buck,daedric/buck,Addepar/buck,daedric/buck,davido/buck,ilya-klyuchnikov/buck,illicitonion/buck,ilya-klyuchnikov/buck,illicitonion/buck,k21/buck,sdwilsh/buck,shybovycha/buck,k21/buck,k21/buck,davido/buck,k21/buck,vschs007/buck,brettwooldridge/buck,SeleniumHQ/buck,k21/buck,nguyentruongtho/buck,ilya-klyuchnikov/buck,zhan-xiong/buck,raviagarwal7/buck,romanoid/buck,nguyentruongtho/buck,SeleniumHQ/buck,illicitonion/buck,shs96c/buck,robbertvanginkel/buck,OkBuilds/buck,grumpyjames/buck,davido/buck,LegNeato/buck,sdwilsh/buck,shybovycha/buck,JoelMarcey/buck,brettwooldridge/buck,OkBuilds/buck,robbertvanginkel/buck,shs96c/buck,k21/buck,romanoid/buck,justinmuller/buck,Addepar/buck,sdwilsh/buck,daedric/buck,robbertvanginkel/buck,LegNeato/buck,vschs007/buck,SeleniumHQ/buck,dsyang/buck,kageiit/buck,JoelMarcey/buck,davido/buck,grumpyjames/buck,brettwooldridge/buck,robbertvanginkel/buck,JoelMarcey/buck,davido/buck,daedric/buck,grumpyjames/buck,dsyang/buck,davido/buck,OkBuilds/buck,daedric/buck,davido/buck,daedric/buck,robbertvanginkel/buck,Addepar/buck,sdwilsh/buck,marcinkwiatkowski/buck,rmaz/buck,brettwooldridge/buck,grumpyjames/buck,sdwilsh/buck,marcinkwiatkowski/buck,SeleniumHQ/buck,ilya-klyuchnikov/buck,raviagarwal7/buck,clonetwin26/buck,dsyang/buck,illicitonion/buck,shs96c/buck,LegNeato/buck,davido/buck,robbertvanginkel/buck,zpao/buck,raviagarwal7/buck,darkforestzero/buck,zhan-xiong/buck,davido/buck,clonetwin26/buck,dsyang/buck,LegNeato/buck,romanoid/buck,Addepar/buck,grumpyjames/buck,sdwilsh/buck,shs96c/buck,darkforestzero/buck,sdwilsh/buck,JoelMarcey/buck,brettwooldridge/buck,brettwooldridge/buck,romanoid/buck,shs96c/buck,zpao/buck,k21/buck,shybovycha/buck,vschs007/buck,LegNeato/buck,SeleniumHQ/buck,OkBuilds/buck,rmaz/buck,grumpyjames/buck,LegNeato/buck,marcinkwiatkowski/buck,romanoid/buck,darkforestzero/buck,justinmuller/buck,brettwooldridge/buck,raviagarwal7/buck,rmaz/buck,daedric/buck,JoelMarcey/buck,darkforestzero/buck,romanoid/buck,raviagarwal7/buck,ilya-klyuchnikov/buck,raviagarwal7/buck,vschs007/buck,shybovycha/buck,justinmuller/buck,SeleniumHQ/buck,Addepar/buck,k21/buck,facebook/buck,JoelMarcey/buck,brettwooldridge/buck,shs96c/buck,romanoid/buck,daedric/buck,clonetwin26/buck,robbertvanginkel/buck,zhan-xiong/buck,dsyang/buck,illicitonion/buck,daedric/buck,rm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