Fix darwin comment
Test r5431691.
- includes:
- # These headers are actually exist in arcadia, so we either should use
- # them and add proper PEERDIR, or should #error them if the are not really used
+ # These headers actually exist in arcadia, so we either should use them and
+ # add proper PEERDIR, or should #error them if they are not really used:
# - bzlib.h
# - db.h
# - expat.h
