[clang] [clang] Clear `NeedsCleaning` flag after `ExpandBuiltinMacro` (PR #133574)

[marius doerner via cfe-commits]

mariusdr wrote:

> LGTM - sorry for the delayed response.
> 
> Will you need me to merge that for you (once the merge conflict is resolved)?

Yes, thanks!

https://github.com/llvm/llvm-project/pull/133574