[clang] [Clang][AST] {CXXDefaultArgExpr, CXXDefaultInitExpr}::hasRewrittenInit return true iff the init expression was really rebuild (PR #99748)

[Shafik Yaghmour via cfe-commits]

https://github.com/shafik commented:

The code mostly makes sense, can we update the summary to clarify the goal of this change? This is what goes in the git log and it is important this is detailed enough to understand the change w/o looking at the details of the change itself.

https://github.com/llvm/llvm-project/pull/99748