Merge remote-tracking branch 'catlee/profile'

* catlee/profile:
  rework profile directory handling
  set output_to_real_object default to false, we get errors handling hardlinks
  Using hardlinks if requested
  comment
  Make sure we only handle known -fprofile flags. Rewrite profile directory to use absolute paths on commandline to increase direct / preprocessed hit rate.
  Move -fprofile handling into cc_process_args
  Look for .gcda files in profile directory when using profile
  Fix profile_use directory, and valgrind warning
  refactor to handle profile directories
  Use hash_delimeter before hashing profile data
  Avoid output_obj being freed by accident
  Fix comment style
  Hash the cwd if we're outputting to our object file first
  handle -fprofile-use
  adding tests
  Get -fprofile-generate, -fprofile-arcs working

diff --cc ccache.c
Simple merge