[C++20] [Modules] Bring Decls Hash to BMI for C++20 Module units#71627

ChuanqiXu9 wants to merge 3 commits intollvm:mainllvm/llvm-project:mainfrom

ChuanqiXu9:DeclsHashChuanqiXu9/llvm-project:DeclsHashCopy head branch name to clipboard