A lot of the default.c module code was refactored. The patch is needed
for the IM.


include/my_sys.h:
  Definitions added.
mysys/default.c:
  Added new api call: process_default_option_files. Also some coments
  changed to reflect current state of the code. It takes Basename for
  config file and the function to process options. The function is called
  everytime when we find an option. This way it is possible to get and
  process options from several groups in one file traversal.
BitKeeper/etc/logging_ok:
  Logging to logging@openlogging.org accepted