[compiler-rt] [ORC_RT][COFF] add more mutex to internal api (PR #112667)

[Wu Yingcong via llvm-commits]

yingcong-wu wrote:

> Note all the public interface already locks the mutex and the functions changed here are only used within the public interface. So, the lock would be redundant.
Okay, good to know that. 

https://github.com/llvm/llvm-project/pull/112667