[llvm] [LLVM][CodingStandard] Extend namespace qualifier rule to variables (PR #163588)

[David Blaikie via llvm-commits]

https://github.com/dwblaikie commented:

I think we might as well generalize this over all declarations, rather than specifying only functions and variables (we shouldn't have many variables declared in headers anyway, but similarly, might have a small number of opaque classes declared in headers too)

https://github.com/llvm/llvm-project/pull/163588