[X86, AVX] replace vextractf128 intrinsics with generic shuffles

[X86, AVX] replace vextractf128 intrinsics with generic shuffles

This is very much like D8088 (checked in at r231792).

Now that we've replaced the vinsertf128 intrinsics,
do the same for their extract twins.

Differential Revision: http://reviews.llvm.org/D8275

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@232052 91177308-0d34-0410-b5e6-96231b3b80d8