[clang] [clang][Sema] Guard polymorphic check in TransformCXXTypeidExpr for incomplete record types (PR #180442)

[Corentin Jabot via cfe-commits]

cor3ntin wrote:

This change needs a release note.
Please add an entry to `clang/docs/ReleaseNotes.rst` in the section the most adapted to the change, and referencing any Github issue this change fixes. Thanks!

https://github.com/llvm/llvm-project/pull/180442