[clang] [Clang] suggest headers on undeclared errors (PR #140247)

[via cfe-commits]

cor3ntin wrote:

We already do have some typo correction https://compiler-explorer.com/z/Ede9rzsn5
I would expect the feature to be plugged into the same place such that:

- If we find a name that is an exact match through lookup
- Otherwise, if there is a name that matches exactly (respecting namespace qualifier) in the known standard names, suggest that
- Otherwise offer typo correction, merging lookup results and standard names (or the first best suggestion of the two)





https://github.com/llvm/llvm-project/pull/140247