[clang] [clang] Add support for MSVC force inline attrs (PR #185282)

[Trung Nguyen via cfe-commits]

================
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -std=c++23 -emit-llvm %s -triple x86_64-pc-windows-msvc -o - | FileCheck %s
+
----------------
trungnt2910 wrote:

Even when optimizations are disabled (`-disable-llvm-passes`), the call sites that are not themselves decorated with `[[msvc::forceinline_calls]]` (or `[[clang::always_inline]]`) will not have the attribute attached.

They will appear as normal function calls, which means we cannot check whether or not the inline attributes are actually working.

https://github.com/llvm/llvm-project/pull/185282