Copy libffi from sxemacs

[XEmacs Webmaster]

Jeff Sparkes writes:

 > Now that RMS has approved GCC's use of dynamically loading plugins,

AFAIK, we don't care what RMS approves of or not, unless he might sue
us for it.  Adding the FFI mechanism is clearly permissible under the
GPL, even though some plausible uses (see below) may not be.

 > we should add FFI to xemacs.

There's already a patch for this, by Steve Youngs.  I thought I put it
on alioth ... indeed, it's there:

http://hg.debian.org/hg/xemacs/xemacs-ffi/

 > Sqlite is not GPL.

But is it copyleft?  As long as it's GPL-compatible (which is
approximately == not copyleft), it's not a problem.