[clang] [Clang] Apply exclude_from_explicit_instantiation to dllimport/dllexport (PR #168171)

[Tomohiro Kashiwada via cfe-commits]

kikairoya wrote:

> That's great! Does this, together with #168170, address the overall problem in #135910, or are there many other issues remaining in order to fix that (other than reverting my old clang change)?

Neither of this nor #168170 is directly related to #135910 itself.
These are prerequisites for libc++'s ABI checking https://github.com/llvm/llvm-project/issues/135910#issuecomment-2901310436 , and another patch and checking functionality itself are still required to upstream.

For #135910 , I already have a "functional" local patch (with exporting nested classes), but I feel that I should try to find more edge cases.

https://github.com/llvm/llvm-project/pull/168171