[clang] [Clang] Allow the use of [[gnu::visibility]] with #pragma clang attribute (PR #145653)

[Nikolas Klauser via cfe-commits]

philnik777 wrote:

@AaronBallman Are any of these concerns specific to `[[gnu::visibility]]`? The exact same concerns seem to apply to any other attribute that applies to functions.

https://github.com/llvm/llvm-project/pull/145653