Update to 2.15.5.

* Do not report on DEBUG as an OPTION. [1]
* Check for use of muted INSTALL_foo commands.
* Warn on use of @dirrm[try].
* Check to make sure rc.d scripts contain a '# PROVIDE:' line. [2]
* Check to see that the options provided to USES are sorted. [3]
* Fix an errant "direct use of command" warning. [4]
* Remove the check to see if StartupNotify is the empty string in
  DESKTOP_ENTRIES.  This is allowed per the spec and per the porter's
  handbook. [5]
* Check for empty lines in plist. [6]
* Check for direct command use in SHEBANG_FILES. [7]

PR:		192525 [1]
		193464 [2]
		193792 [3]
		193793 [4]
		193456 [5]
		193794 [6]
		193795 [7]
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