[clang] Split -Wcast-function-type into a separate group (PR #86131)

[Peter Dimov via cfe-commits]

pdimov wrote:

I get the warning for your code.
```
1>testbed2022.cpp(8,15): warning : cast from 'FARPROC' (aka 'long long (*)()') to 'PGNSI' (aka 'void (*)(_SYSTEM_INFO *)') converts to incompatible function type [-Wcast-function-type-mismatch]
```
Make sure you're passing /W4 to clang-cl.

https://github.com/llvm/llvm-project/pull/86131