[llvm] [IR][ASMParser] Use default AS for alloca without explicit AS (PR #135786)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm requested changes to this pull request.

I don't think this should be done. It's inconsistent behavior with every other context in the IR. The other case that tries to behave like this is the program address space, but that is confusing and should be removed. The syntax should be consistent, without context 

https://github.com/llvm/llvm-project/pull/135786