[clang] [Clang] remove qualifiers in getCanonicalTypeUnqualified (PR #170271)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman commented:

The changes LGTM but I do have a question: any time we change how type traits are resolved, we silently break ABI for some users. Should we have an ABI versioning check so people can get the old behavior back if they need to? I don't think `__is_pointer_interconvertible_base_of()` is used so often that we need to (https://sourcegraph.com/search?q=context:global+lang:C%2B%2B+__is_pointer_interconvertible_base_of+count:10000000+-file:.*clang.*+-file:.*test.*&patternType=keyword&sm=0) but I still think the question is worth asking others.

https://github.com/llvm/llvm-project/pull/170271