Handle Solaris 8/9 x86 as rep syntax

[Uros Bizjak]

Hello!

> During a recent 4.4 bootstrap on Solaris 9/x86 with Sun as, I noticed
> that this version of the assembler cannot deal with rep <insn>, but
> requires rep; <insn> instead.  gas can handle both forms, and both
> i386.c and xmmintrin.h already use the latter, so this seems obvious.

"rep" with a semicolon will disable following warning from gas:

empty.s: Assembler messages:
empty.s:9: Error: expecting string instruction after `rep'

While it is OK for "rep; nop" and "rep; ret" to disable the warning,
it is OK for string instructions.

Uros.