[clang] [llvm] Add support for Windows hot-patching (PR #138972)

[Alexandre Ganea via cfe-commits]

================
@@ -0,0 +1,18 @@
+// This verifies that hotpatch function attributes are correctly propagated through LLVM IR when compiling with LTO.
+//
+// RUN: %clang_cl -c --target=x86_64-windows-msvc -O2 /Z7 -fms-hotpatch-functions-file=%S/ms-hotpatch-functions.txt -flto /Fo%t.bc %s
----------------
aganea wrote:

If you wish, you could also you `split-file` before this line to keep the test self-contained. See https://llvm.org/docs/TestingGuide.html#extra-files

https://github.com/llvm/llvm-project/pull/138972