[C++] unknown argument: '-Kc++'

### Describe the bug, including details regarding any error messages, version, and platform.

I'm trying to build arrow@19.0.1 which pulls in `mimalloc` (ARROW_MIMALLOC_BUILD_VERSION=v2.0.6). I am using the Intel OneAPI 2025.x compiler suite, which is Clang/LLVM based. This check doesn't seem to correctly detect this compiler:
https://github.com/microsoft/mimalloc/blob/09a27098aa6e9286518bd9c74e6ffa7199c3f04e/CMakeLists.txt#L361

resulting in
```
-- stderr output is:
icpx: error: unknown argument: '-Kc++'
icpx: warning: treating 'c' input as 'c++' when in C++ mode, this behavior is deprecated [-Wdeprecated]
make[5]: *** [CMakeFiles/mimalloc-static.dir/build.make:82: CMakeFiles/mimalloc-static.dir/src/stats.c.o] Error 1
make[4]: *** [CMakeFiles/Makefile2:90: CMakeFiles/mimalloc-static.dir/all] Error 2
make[3]: *** [Makefile:139: all] Error 2
```

I've also reported this upstream https://github.com/microsoft/mimalloc/issues/1153

### Component(s)

C++