[COMMIT] Support Ghe with upturn in X11

[stephen at xemacs.org]

Andriy Gapon writes:

 > BTW, maybe you will find this interesting/useful: some time ago I
 > stumbled upon a function called KeySymToUcs4 in xfree86 4.5.0 sources in
 > file imConv.c. I am sure it should be there in x.org too. I think that
 > this function is not externally visible,

Thank you for pointing this out, but I think we should decline.

Experience says that calling internal X11 functions leads to madness.
Open source X11 code does almost no error checking, and often requires
callers to obey undocumented restrictions.  (Probably we can borrow
the code, though.)  Also, there will be several platforms (TTY,
Windows, Aqua at least) where we need to do similar operations, and
that code should be as much shared as possible.