[clang] [clang] Fix type of the MaterializeTemporaryExpr with incomplete array type. (PR #187618)

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

Added ast-dump test.  Not sure how helpful that is, but it should at least clarify what I'm fixing.

https://github.com/llvm/llvm-project/pull/187618