coffdu-rs6000.{lo,c}.
(coff-pmac.lo, coff-rs6000.lo, coff64-rs6000.lo): Add dependency
on xcoff.h
* Makefile.in: Regenerate.
* xcoff.h: New file.
* coff-pmac.c: Use xcoff.h instead of coff-rs6000.c.
* coff-rs6000.c: Move all declarations and defines that are
common to the xcoff backends into xcoff.h
* coff64-rs6000.c: Ditto,