[llvm] [Support] Fix the style of type aliases (NFC) (PR #157141)

[Kazu Hirata via llvm-commits]

kazutakahirata wrote:

> IIUC you meant type alias.
> 
> https://cppreference.com/w/cpp/language/type_alias.html https://cppreference.com/w/cpp/language/namespace.html#Using-directives

@zwuis That's better.  I've corrected the title and commit message.  Thank you for pointing this out!


https://github.com/llvm/llvm-project/pull/157141