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

[Rose Hudson via cfe-commits]

rosefromthedead wrote:

@mizvekov @AaronBallman with the above in mind, does the patch still look good to you? If so, please merge it. I don't have commit rights.

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