[clang] [clang-tools-extra] [clang] AST: fix getAs canonicalization of leaf types (PR #155028)

[Matheus Izvekov via cfe-commits]

mizvekov wrote:

@jyknight thanks, this will be fixed here: https://github.com/llvm/llvm-project/pull/155900

https://github.com/llvm/llvm-project/pull/155028