[cpp-extensions] Add clang to the list of supported Linux compilers (#103349)
Not sure, why was it excluded previous (oversight I guess).
Also, please note, that `clang++` is already considered acceptable compiler (as it ends with `g++` ;))
<!--
copilot:poem
-->
### <samp>🤖 Generated by Copilot at 55aa7db</samp>
> _`clang` or `gcc`, we don't care what you use_
> _We'll build our extensions with the tools we choose_
> _Don't try to stop us with your version string_
> _We'll update our logic and make our code sing_
Pull Request resolved: https://github.com/pytorch/pytorch/pull/103349
Approved by: https://github.com/seemethere
