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

[Devon Loehr via cfe-commits]

DKLoehr wrote:

This is breaking builds when compiling chromium as well, bisected to this change. Example build: https://ci.chromium.org/ui/p/chromium/builders/ci/ToTLinux%20(dbg)/31974/overview. Compiler output can be seen by clicking `[raw]` under the `compile` step, but I'm working on a minimized reproduction now.

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