[clang] [llvm] [Clang] Fix argument extensions in CGBlocks.cpp (PR #111740)

[Nikita Popov via cfe-commits]

https://github.com/nikic commented:

> I realize this is not the approach you had in mind, but it would at least be nice to hear the reasoning as to why something more elaborate would be preferred?

Basically, because this is an ABI-dependent property, so we should let the existing ABI handling code deal with it.

I can't think of an example where something would go wrong in *this* particular case, because I don't think any target uses zeroext for `int`. But for `unsigned` there is a mix of targets using zeroext or signext (or neither of course).

https://github.com/llvm/llvm-project/pull/111740