[clang] [llvm] [CMake] Add a linker test for -Bsymbolic-functions to AddLLVM (PR #79539)

[Brad Smith via cfe-commits]

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@@ -314,6 +308,11 @@ function(add_link_opts target_name)
     set_property(TARGET ${target_name} APPEND_STRING PROPERTY
                  LINK_FLAGS " -Wl,-brtl")
   endif()
+
+  if (NOT MINGW)
+    llvm_check_linker_flag(CXX "-Wl,-Bsymbolic-functions"
+                           LINKER_SUPPORTS_B_SYMBOLIC_FUNCTIONS)
+  endif()
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brad0 wrote:

That didn't make any sense to me. Which ```if``` and which PR?

https://github.com/llvm/llvm-project/pull/79539