[X86][SSE] Combine EXTRACT_VECTOR_ELT with combineExtractWithShuffle before XFormVExt...

[X86][SSE] Combine EXTRACT_VECTOR_ELT with combineExtractWithShuffle before XFormVExtractWithShuffleIntoLoad

combineExtractWithShuffle can handle more complex shuffles/bitcasts than we can with the equivalent code in XFormVExtractWithShuffleIntoLoad.

Mainly a compile time improvement now (combineExtractWithShuffle combines will have always failed late on inside XFormVExtractWithShuffleIntoLoad), and will let us merge combineExtractVectorElt_SSE in a future commit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@317481 91177308-0d34-0410-b5e6-96231b3b80d8