Add stdlib.h so sym_upload.cc finds exit() [backport]
Add stdlib.h so sym_upload.cc finds exit() [backport]

bbcallen/google-breakpad,Quiark/google-breakpad,mhoran/google-breakpad,mhoran/google-breakpad,mhoran/google-breakpad,mhoran/google-breakpad,bbcallen/google-breakpad,Quiark/google-breakpad,Quiark/google-breakpad,bbcallen/google-breakpad,Quiark/google-breakpad,bbcallen/google-breakpad,mhoran/google-breakpad,bbcallen/google-breakpad,mhoran/google-breakpad,Quiark/google-breakpad,Quiark/google-breakpad,bbcallen/google-breakpad