[clang] [clang-tools-extra] [clang-tidy][use-internal-linkage]fix false positives for ExportDecl (PR #117901)

[Piotr Zegar via cfe-commits]

https://github.com/PiotrZSL requested changes to this pull request.

Documentation & Test for matcher is missing.
Except that everything looks ok.

https://github.com/llvm/llvm-project/pull/117901