GDB uses a number of autoconf macros found in bfd/acinclude.m4.  It 
accesses them by sucking in the entire contents of that file (creating 
sinclude hell).

This patch moves those macros to a new file bfd/bfd.m4 so that GDB can 
include them directly.  After aclocal/autoconf this still rebuilt on a 
PPC and amd64 GNU/Linux systems.

Ok?

Andrew