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

[Jan Patrick Lehr via cfe-commits]

jplehr wrote:

I think this broke one of our bots: https://lab.llvm.org/buildbot/#/builders/10/builds/3726/steps/10/logs/stdio

The bot was red for another issue at the time, but the stack trace includes methods that are touched in this PR.
This is part of the stack trace:
```
#12 0x0000748dc31b00cb clang::LinkageComputer::computeTypeLinkageInfo(clang::Type const*) (/home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/bin/../lib/../lib/libclangAST.so.21.0git+0xbb00cb)
#13 0x0000748dc31b0b9b clang::LinkageComputer::getTypeLinkageAndVisibility(clang::Type const*) (/home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/bin/../lib/../lib/libclangAST.so.21.0git+0xbb0b9b)
#14 0x0000748dc2af0258 clang::LinkageComputer::getLVForTemplateArgumentList(llvm::ArrayRef<clang::TemplateArgument>, clang::LVComputationKind) (/home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/bin/../lib/../lib/libclangAST.so.21.0git+0x4f0258)
#15 0x0000748dc2af05d1 clang::LinkageComputer::mergeTemplateLV(clang::LinkageInfo&, clang::ClassTemplateSpecializationDecl const*, clang::LVComputationKind) (/home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/bin/../lib/../lib/libclangAST.so.21.0git+0x4f05d1)
#16 0x0000748dc2af120c clang::LinkageComputer::getLVForNamespaceScopeDecl(clang::NamedDecl const*, clang::LVComputationKind, bool) (/home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/bin/../lib/../lib/libclangAST.so.21.0git+0x4f120c)
#17 0x0000748dc2aeee05 clang::LinkageComputer::getLVForDecl(clang::NamedDecl const*, clang::LVComputationKind) (/home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/bin/../lib/../lib/libclangAST.so.21.0git+0x4eee05)
```

I'd appreciate if someone more familiar with the matter can have a look at it. I'm happy to assist with info on build config etc.

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