[clang] [Clang] Make the result type of sizeof/pointer subtraction/size_t lit… (PR #136542)

[Matheus Izvekov via cfe-commits]

mizvekov wrote:

If you make it a canonical node, you also automatically don't get an `aka` in diagnostics, which might be an advantage (or not).

Ie you avoid the aka in `size_t (aka 'unsigned long')` you currently get.

https://github.com/llvm/llvm-project/pull/136542