[clang] [clang] Handle instantiated members to determine visibility (PR #136128)

[Erich Keane via cfe-commits]

erichkeane wrote:

Revert submitted here: https://github.com/llvm/llvm-project/pull/136317 

When CI is ok with it, I'll merge it.

https://github.com/llvm/llvm-project/pull/136128