Fix java_compile postprocessing.
Fix java_compile postprocessing.

It's now correct in the presence of cached artifacts.

Auditors: markcc

pombredanne/commons,nkhuyu/commons,VaybhavSharma/commons,brutkin/commons,ericzundel/commons,jsirois/commons,Yasumoto/commons,Yasumoto/commons,Yasumoto/commons,WCCCEDU/twitter-commons,nkhuyu/commons,cevaris/commons,atollena/commons,WCCCEDU/twitter-commons,nkhuyu/commons,brutkin/commons,jsirois/commons,Yasumoto/commons,ericzundel/commons,pombredanne/commons,abel-von/commons,cevaris/commons,ericzundel/commons,abel-von/commons,imsut/commons,nkhuyu/commons,atollena/commons,cevaris/commons,WCCCEDU/twitter-commons,imsut/commons,ericzundel/commons,WCCCEDU/twitter-commons,VaybhavSharma/commons,atollena/commons,pombredanne/commons,brutkin/commons,WCCCEDU/twitter-commons,VaybhavSharma/commons,cevaris/commons,VaybhavSharma/commons,jsirois/commons,abel-von/commons,jsirois/commons,brutkin/commons,Yasumoto/commons,abel-von/commons,atollena/commons,jsirois/commons,ericzundel/commons,atollena/commons,cevaris/commons,VaybhavSharma/commons,imsut/commons,abel-von/commons,nkhuyu/commons,pombredanne/commons,brutkin/commons,pombredanne/commons