[COMMIT] Eliminate some non-X11 build failures

[Aidan Kehoe]

 Ar an cúigiú lá déag de mí Deireadh Fómhair, scríobh Stephen J. Turnbull: 

 > [...] In fact, I don't see a point to doing multiple test builds for
 > different builds of XEmacs of a given version at all. I'm not an expert
 > on the byte- compiler, but AFAIK in the absence of compilation
 > conditioned on features there should be no differences between a package
 > byte-compiled by an X11 build and one byte-compiled by a non-X11 build of
 > XEmacs.

It’s quite easy to have a compile-time dependency on X11 if; you just need
top-level code in one file that calls an X11-specific function, together
with a #'require of that file from another file (since #'require calls are
surrounded by an implicit #'eval-and-compile). x-symbol fails on a non-X11
build for a similar reason right now, though my memory of the details isn’t
particularly clear and I haven’t sshed to my home machine to check if that’s
exactly it.

More generally, there’s no guarantee that X11 will always be XEmacs’ primary
platform, and not requiring it would make it easier to implement smoketests
for failures on Win32 and Carbon.

-- 
On the quay of the little Black Sea port, where the rescued pair came once
more into contact with civilization, Dobrinton was bitten by a dog which was
assumed to be mad, though it may only have been indiscriminating. (Saki)