[llvm] [CGData] Lazy loading support for stable function map (PR #151660)

[Zhaoxuan Jiang via llvm-commits]

nocchijiang wrote:

> Looks like this doesn't build with libc++: http://45.33.8.238/macm1/112476/step_3.txt Probably needs an `#include <map>` in StableFunctionMap.h for `unordered_map`? Please take a look and revert for now if it takes a while to fix.

@nico Could you please tell me how to reproduce the build locally? I am working on an Apple Silicon Mac and have tried `-DLLVM_ENABLE_LIBCXX=On` but cannot reproduce it.

https://github.com/llvm/llvm-project/pull/151660