[llvm] ARM: Remove check for isAAPCS_ABI when enabling various aeabi calls (PR #152108)

[Eli Friedman via llvm-commits]

https://github.com/efriedma-quic commented:

You can directly specify the ABI using the clang "-mabi" flag on 32-bit ARM.  Given that functionality exists, probably someone is using it somehow.

If we want to rip out support for using -mabi to switch the ABI on 32-bit Arm targets, I wouldn't be opposed; it's not really useful to generate code with the wrong ABI.  But if we do, we should rip it out all at once, with an explicit hard error in clang, not subtly break it over time.

https://github.com/llvm/llvm-project/pull/152108