[clang] [clang] use ArrayTypeTraitExpr::getType as value type (PR #113186)

[Eli Friedman via cfe-commits]

https://github.com/efriedma-quic approved this pull request.

Please make the title of the pull request something more useful, like "[clang codegen] fix crash emitting __array_rank".  The current title is utterly useless for someone looking through the commit history.

LGTM with comments addressed.

https://github.com/llvm/llvm-project/pull/113186