build: fix 9562a77... (mrlg removal)

mrlg.cgi was removed in 9562a77 "mrlg: Remove obsolete version." but the
file was still listed in Makefile.am.

Fixes: 9562a77 ("mrlg: Remove obsolete version.")
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
1 file changed