arch/microblaze: add new architecture

Add Microblaze architecture support.

This depends on EXPERIMENTAL, as upstream projects do not yet
include full support to build a modern microblaze compiler.
This is in the process of being updated, but is not currently
publicly accessible.

Signed-off-by: "David Holsgrove" <david.holsgrove@xilinx.com>
Message-Id: <9c93e18b3d68b19303f3.1348113870@localhost.localdomain>
PatchWork-ID: 185305

 --- a/bfd/elf32-arm.c

 +++ b/bfd/elf32-arm.c

 @@ -12408,7 +12408,8 @@ elf32_arm_check_relocs (bfd *abfd, struc

  	  /* If the symbol is a function that doesn't bind locally,

  	     this relocation will need a PLT entry.  */

 -	  root_plt->refcount += 1;

 +	  if (root_plt->refcount != -1)

 +	    root_plt->refcount += 1;

  	  if (!call_reloc_p)

  	    arm_plt->noncall_refcount++;