[clang] [clang][libclang]Check auto type for type constraints (PR #172472)

[via cfe-commits]

Serafean wrote:

> Thank you! The changes LGTM but this should have a release note in `clang/docs/ReleaseNotes.rst` so others know about the new API.

Thank you for taking the time! I'll add 
```
index e43ded2a88c1..6b1fc022adb5 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -776,6 +776,7 @@ clang-format
 
 libclang
 --------
+- Visit constraints of `auto` type to properly visit concept usages
```
rebase on main and force push tonight. 

https://github.com/llvm/llvm-project/pull/172472