[X86] Update fast-isel tests for clang r335253.

[X86] Update fast-isel tests for clang r335253.

The new IR fixes a mismatch in the final extractelement for the i32 intrinsics. Previously we extracted a 64-bit element even though we only wanted 32 bits.

SimplifyDemandedElts isn't able to make FP elements undef now and the shuffle mask I used prevents the use of horizontal add we had before. Not sure we should have been using horizontal add anyway. It's implemented on Intel with two port 5 shuffles and an add. So we have on less shuffle now, but an additional instruction to decode.

Differential Revision: https://reviews.llvm.org/D48347

llvm-svn: 335256