Merging r182364:

------------------------------------------------------------------------
r182364 | d0k | 2013-05-21 02:58:54 -0700 (Tue, 21 May 2013) | 4 lines

X86: When emulating unsigned PCMPGTQ with PCMPGTD, fix the sign bit for the smaller type.

Otherwise we'll get a mix of signed and unsigned compares.
Fixes PR15977.
------------------------------------------------------------------------


git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_33@182413 91177308-0d34-0410-b5e6-96231b3b80d8