[clang] [Clang] Add __ugly__ spelling for the msvc attribute scope (PR #113765)

[Nikolas Klauser via cfe-commits]

philnik777 wrote:

> How would that be used? MSVC seems to not like the ugly spelling https://compiler-explorer.com/z/Kb85YY18P

We need `[[msvc::no_unique_address]]` in libc++ for Windows but don't support MSVC, only clang-cl, so we can make use of this spelling to avoid grabbing the tokens. FWIW the MSVC STL has a similar problem and I hope MSVC will follow suit. Maybe @StephanTLavavej has some thoughts as well.


https://github.com/llvm/llvm-project/pull/113765