Broadcom XLP support

[Maciej W. Rozycki]

Hi Andy,

> {standard input}: Assembler messages:
> {standard input}:215: Error: unrecognized opcode `msgsnds $3,$4'
> {standard input}:280: Error: unrecognized opcode `msgsnds $3,$4'
> {standard input}:339: Error: unrecognized opcode `msgsnds $3,$4'
> {standard input}:361: Error: unrecognized opcode `msgsnds $3,$4'
> {standard input}:420: Error: unrecognized opcode `msgsnds $3,$4'
> {standard input}:442: Error: unrecognized opcode `msgsnds $3,$4'
> {standard input}:490: Error: unrecognized opcode `msglds $2,$4'
> {standard input}:558: Error: unrecognized opcode `msglds $2,$4'
> 
> The only thing that changed was my patch to binutils, so, I'm expecting
> that I screwed something up/left something out.  If you have anything
> that could help me out to figure this out, I would appreciate it.

 Make sure INSN_XLP is set to something sane too.  Unlike E_MIPS_MACH_XLP 
it's a part of an internal API only, so you only need to make sure it is 
unambiguous and that it does not overlap with INSN_ISA_MASK.

 I think it's as much guidance I can give you for an external patch.  If 
you want proper support (and E_MIPS_MACH_XLP fixed in the ABI), then I 
suggest persuading Broadcom to submit their change properly for inclusion 
with FSF sources.  I'll be happy to review it.

 HTH,

  Maciej