[ms-inline asm] When parsing inline assembly we set the base register to a

[ms-inline asm] When parsing inline assembly we set the base register to a
non-zero value as we don't know the actual value at this point.  This is
necessary to get the matching correct in some cases.  However, the actual value
set as the base register doesn't matter, since we're just matching not emitting.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166523 91177308-0d34-0410-b5e6-96231b3b80d8