Fix for simple memory leak that was assigned CVE-2019-6128.
pal2rgb failed to free memory on a few errors. This was reported here: http://bugzilla.maptools.org/show_bug.cgi?id=2836.
pal2rgb failed to free memory on a few errors. This was reported here: http://bugzilla.maptools.org/show_bug.cgi?id=2836.