[X86] Use a MOVSX instruction instead of a MOVZX instruction in isel for an any_exten...

[X86] Use a MOVSX instruction instead of a MOVZX instruction in isel for an any_extend of the remainder from an 8-bit sdivrem.

The sdivrem will emit its own MOVSX to move %ah to the low byte of a register. By using a MOVSX for an any_extend this allows a post-isel peephole to merge them.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@346581 91177308-0d34-0410-b5e6-96231b3b80d8