[libffi] Unwind info for x86_64

[Andrew Haley]

Andreas Jaeger writes:
 > 
 > Andrew,
 > 
 > can you add your x86-64 java patches also to the GCC 3.3 branch,
 > please?
 > 
 > I think this patch was only applied to mainline so far:
 >         2003-01-10  Andrew Haley  <aph@redhat.com>
 > 
 >         * include/dwarf2-signal.h: Remove x86_64.
 >         * configure.host (x86_64 DIVIDESPEC): Remove.
 >         * include/x86_64-signal.h: New file.
 >         * configure.in: Regenerate.

Patience.  All will be checked in when I have test results.

Andrew.