[clang] [llvm] Add support for Windows Secure Hot-Patching (PR #138972)

[Eli Friedman via llvm-commits]

https://github.com/efriedma-quic commented:

I'd like to see regression tests for the cases I've mentioned.  PHI nodes, ConstantExpr, and I guess the combination of the two.

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