Create a single multiclass for SSE and AVX version of MOVL/MOVH. Prevents needing to specify everything twice. No functional change intended

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172378 91177308-0d34-0410-b5e6-96231b3b80d8
Simplify nested strconcats in X86 td files since strconcat can take more than 2 arguments.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172379 91177308-0d34-0410-b5e6-96231b3b80d8