[ms] [X86] Use "P" modifier on operands to call instructions in inline X86 assembly.

[ms] [X86] Use "P" modifier on operands to call instructions in inline X86 assembly.

Summary:
This is documented as the appropriate template modifier for call operands.
Fixes PR44272, and adds a regression test.

Also adds support for operand modifiers in Intel-style inline assembly.

Reviewers: rnk

Reviewed By: rnk

Subscribers: merge_guards_bot, hiraditya, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D71677