[llvm] ARM: Start moving runtime libcall configuration out of TargetLowering (PR #142617)

[Aiden Grossman via llvm-commits]

boomanaiden154 wrote:

> The whole point of doing this is the RuntimeLibcallInfo uses outside of TargetLowering are wrong; they will incorrectly see the default function names which won't actually be used with the target.

I don't think that matters here. `__rt_sdiv` will end up getting used with this target triple to lower `sdiv` instructions.

> The test probably needs updating to the correct libcall name

The libcall name in the test is correct, at least as far as I can tell. The `sdiv` lowers to ` __rt_sdiv` libcall and produces an undefined symbol error if I drop the file defining `__rt_sdiv`:

```
lld-link: error: undefined symbol: __rt_sdiv
>>> referenced by /home/gha/llvm-project/build/tools/lld/test/COFF/Output/lto-late-arm.ll.tmp.exe.lto.obj:(entry)
```

I am unsure if the LTO infrastructure that figures out what needs to be imported is doing the correct thing here though. I can readd the test/mark it as XFAIL if this is expected to return to the same behavior at some point.

https://github.com/llvm/llvm-project/pull/142617