* vmsdbg.h, vmsdbgout.c: Add documentation and minor cleanups.
	* doc/invoke.texi: Add -gvms.
	* doc/passes.texi: Add mention of vmsdbgout.c.
	* doc/tm.texi: Document VMS debugging output.

Co-Authored-By: Douglas B Rupp <rupp@gnat.com>

From-SVN: r47668