[CM] openmcl CLM load problem

[Bill Schottstaedt]

If X11 has been installed, with the headers, then you need to add
the directory to the PATH variable, or something like that.  Where
is X11/Xlib.h?  You could add the path to the *cflags* setting
in all.lisp under mac-osx -- currently it has -I/usr/X11R6/include.
Someone sent me code to check that the X11 headers were accessible
before trying to compile/load sc.c, but it got buried in my TODO
list.