[clang] [llvm-profdata] Do not create numerical strings for MD5 function names read from a Sample Profile. (PR #66164)

[William Junda Huang via cfe-commits]

huangjd wrote:

It looks like after using HashKeyMap, the purpose of SymbolMap and GUIDToFuncNameMap can be merged. SymbolMap maps StringRef to Function*, GUIDToFuncNameMap maps ProfileFuncRef's hash code to StringRef, and it's almost exclusively cascaded to SymbolMap lookup, so we can actually combine two maps into one, saving a lot of time. 

https://github.com/llvm/llvm-project/pull/66164