[ms-inline asm] Have the TargetParser callback to Sema to determine the size of

[ms-inline asm] Have the TargetParser callback to Sema to determine the size of
a memory operand.  Retain this information and then add the sizing directives
to the IR.  This allows the backend to do proper instruction selection.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166316 91177308-0d34-0410-b5e6-96231b3b80d8