RFR : fix Assembler::prefix_and_encode for x86

[Doug Simon]

Are you sure this fix should be made in the Graal code base? Seems like an upstream patch to me.

> On Jan 13, 2015, at 10:58 AM, Igor Ignatyev <igor.ignatyev at oracle.com> wrote:
> 
> Hi all,
> 
> please review the fix for Assembler::prefix_and_encode method for 32bit:
> 16064:03eda0a202e9 changed signature of this method and implementation for 64bit (in assembler_x86.cpp), however 32bit inline version wasn't changed.
> 
> http://cr.openjdk.java.net/~iignatyev/graal/i586_prefix_and_encode/webrev.00/
> 
> -- 
> Thanks,
> Igor