Remove bundled wrlib stuff

This patch removes bits and pieces of xmu that for some reason
have been bundled with wmaker. I can very well imagine that at the time
they were bundled, xmu was not, was not available everywhere, or
whatever.

I couldn't come across a system that doesn't have these things in its
system-supplied x libs, though i've been carrying this since january,
and my memory is quite flakey at times.

certainly nothing xorg is at danger, nor xfree86 dating back to at
least 3.3. i believe this stuff should be everywhere that calls itself
to be on par with x11r6.3 at the very least.

it would be incredibly useful if people having access to commercial
unixes could check this on things released in the past, say, 15 years.
i believe back then i had solaris 8+and sco openserver 5+ covered.

wrlib/context.c

@@ -24,6 +24,7 @@
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
 #include <X11/Xatom.h>
+#include <X11/Xmu/StdCmap.h>
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -32,8 +33,6 @@
 
 #include <math.h>
 
-#include "StdCmap.h"
-
 #include "wraster.h"
 
 extern void _wraster_change_filter(int type);