LU-14703 build: fixup lustre-libcfs.m4 comments

LU-14703 build: fixup lustre-libcfs.m4 comments

Several macros whose ends are commented to identify the macro being
defined, like

.. # LIBCFS_FUBAR

have the wrong macro named in the comment.  Fix those
end comments so they match the opening comment or the
AC_DEFUN correctly.

Test-Parameters: trivial
Change-Id: Ia40ccb9e271e90306df37d0028734a84684e42ef
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Reviewed-on: https://review.whamcloud.com/43776
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Minh Diep <mdiep@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>