[clang-tools-extra] [clang-doc] Wrap per thread arenas in an accessor for BUILD_SHARED (PR #201388)

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trcrsired wrote:

i am trying to build this with your patch right now.

Also here is another thing that has to do with clang-tidy for BUILD_SHARED_LIBS but the patch seems to break CI. do not know how to fix it.
https://github.com/llvm/llvm-project/pull/96856

https://github.com/llvm/llvm-project/pull/201388