[compiler-rt] [builtins][AArch32] Fix __gnu_* functions (PR #137638)

[Peter Smith via llvm-commits]

https://github.com/smithp35 commented:

Your description will become the commit message (can be altered at squash and merge time). 

Will be worth rewriting it to be closer to the intended commit message if you don't have commit access.

Will be worth mentioning that the `__gnu_h2f_ieee` and `__gnu_f2h_ieee` functions in Arm use the base-standard ABI like the `__aeabi_` functions so we must use a call for hard-float Arm targets but can use an alias for base-standard targets. 

https://github.com/llvm/llvm-project/pull/137638