rust: make sure build output files are recorded
rust: make sure build output files are recorded

Summary:
buildableContext.recordArtifact() must be called to make
sure the build output is cached properly. Failing to call it succeeds
silently, in that the file exists, and is available to later build
steps, but it's not included in the cache, so later cache hits will
fail to find it.

Test Plan:
$ rm -rf buck-out/
$ buck build --config cache.mode=dir //rust/project/...
$ rm -rf buck-out/gen/
$ buck build --config cache.mode=dir //rust/project/...

This will do a build and cache the results, remove the build, then
rebuild relying on the cache. Previously this failed because the
cache was incomplete.

Reviewed By: bolinfest

fbshipit-source-id: 824a55b

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