Many files:

Many files:
  get_device_by_label.h (get_volume_label_by_spec): Add function prototype.
  get_device_by_label.c: Use string_copy() instead of strdup() for
  	portability's sake.  Fix a few other gcc -Wall complaints.
  fsck.h, fsck.c (string_copy): Export string_copy() extern.
  badblocks.c: Fix various gcc -Wall complaints, including an incorrect
  	reference to sync in flush_bufs().
ChangeLog, configure, configure.in:
  configure.in: Add checks for the header files sys/mkdev.h and
  	sys/sysmacros.h.