[llvm] AMDGPU: Verify function type matches when matching libcalls (PR #119043)

[Jan Patrick Lehr via llvm-commits]

jplehr wrote:

I believe this patch turned the HIP buildbot red https://lab.llvm.org/buildbot/#/builders/123/builds/11310
So far, I was unable to reproduce the error locally.
It reaches an unreachable:
```
Unhandled param type
UNREACHABLE executed at /buildbot/llvm-project/llvm/lib/Target/AMDGPU/AMDGPULibFunc.cpp:961!
<...>
#10 0x000055d3fc651f98 llvm::AMDGPUMangledLibFunc::getFunctionType(llvm::Module const&) const (/buildbot/hip-vega20-0/clang-hip-vega20/llvm/bin/clang-19+0x130ff98)
#11 0x000055d3fc64f7c9 llvm::AMDGPULibFunc::isCompatibleSignature(llvm::Module const&, llvm::FunctionType const*) const (/buildbot/hip-vega20-0/clang-hip-vega20/llvm/bin/clang-19+0x130d7c9)
#12 0x000055d3fc649601 llvm::AMDGPULibCalls::fold(llvm::CallInst*) (/buildbot/hip-vega20-0/clang-hip-vega20/llvm/bin/clang-19+0x1307601)
#13 0x000055d3fc64a3df llvm::AMDGPUSimplifyLibCallsPass::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/buildbot/hip-vega20-0/clang-hip-vega20/llvm/bin/clang-19+0x13083df)
```

https://github.com/llvm/llvm-project/pull/119043