[clang] [Clang] Add explicit visibility symbol macros (PR #108276)

[Saleem Abdulrasool via cfe-commits]

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@@ -166,7 +166,7 @@ if(ENABLE_SHARED)
     set_target_properties(libclang
       PROPERTIES
       VERSION ${LIBCLANG_LIBRARY_VERSION}
-      DEFINE_SYMBOL _CINDEX_LIB_)
+      DEFINE_SYMBOL _CINDEX_LIB_  DEFINE_SYMBOL CLANG_EXPORTS)
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compnerd wrote:

This will override the `_CINDEX_LIB_` symbol, so this seems incorrect.

https://github.com/llvm/llvm-project/pull/108276