Simplify. We already know we have hidden visibility at this point.

Modules/GenerateExportHeader.cmake

@@ -248,12 +248,10 @@ function(add_compiler_export_flags)
     endif()
   endif()
 
-  if(USE_COMPILER_HIDDEN_VISIBILITY AND COMPILER_HAS_HIDDEN_VISIBILITY AND NOT _GCC_COMPILED_WITH_BAD_ALLOCATOR)
-    set (EXTRA_FLAGS "-fvisibility=hidden")
+  set (EXTRA_FLAGS "-fvisibility=hidden")
 
-    if(COMPILER_HAS_HIDDEN_INLINE_VISIBILITY)
-      set (EXTRA_FLAGS "${EXTRA_FLAGS} -fvisibility-inlines-hidden")
-    endif()
+  if(COMPILER_HAS_HIDDEN_INLINE_VISIBILITY)
+    set (EXTRA_FLAGS "${EXTRA_FLAGS} -fvisibility-inlines-hidden")
   endif()
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${EXTRA_FLAGS}" PARENT_SCOPE)
 endfunction()