[clang] [Clang][Sema] Diagnose variable template explicit specializations with storage-class-specifiers (PR #93873)

[David Blaikie via cfe-commits]

dwblaikie wrote:

Sent a patch to add a warning flag for the warning this patch uses: https://github.com/llvm/llvm-project/pull/96699

With that, we could disable the warning during the compiler migration, decoupling compiler migration from code cleanup.

https://github.com/llvm/llvm-project/pull/93873