[clang] Mark CXX module initializer with PACBTI attributes (PR #133716)

[Eli Friedman via cfe-commits]

================
@@ -0,0 +1,72 @@
+// RUN: %clang_cc1 -triple thumbv8.1m.main-unknown-none-eabi -emit-module-interface -target-feature +pacbti -mbranch-target-enforce -std=c++20 %s -o %t.pcm
----------------
efriedma-quic wrote:

I don't think we need all the combinations here in RUN lines; we verify that elsewhere. The important thing is just that the attributes are getting computed at all.

https://github.com/llvm/llvm-project/pull/133716