Rewrite parse_config_file(). Among the old version's problems:

Rewrite parse_config_file().  Among the old version's problems:
  No checking for lines that were too long.
  No checking that fgets returning NULL was actually due to EOF.
  Various whitespace handling inconsistencies.
  Bloat (switches and multiple identical function calls).
  Failure to check for trailing characters in some cases.
  Dynamicly allocated memory was not free()d on error.
Given that this controls suid/sgid behavior, the sloppy coding was
really inexcusable.  :-(