[clang] [llvm] [clang][ssaf] Add the TUSummaryExtractorRegistry (PR #173290)

[Tomohiro Kashiwada via cfe-commits]

https://github.com/kikairoya commented:

@steakhal Hi, this change doesn't work in MinGW/Cygwin with `-DCLANG_LINK_CLANG_DYLIB=ON` due to wrong instantiations of `llvm::Registry<...>`. Those hosts require proper declarations of the template instantiations to share data symbols across DLL boundaries.
Could you take a look?

https://github.com/llvm/llvm-project/pull/173290