no rt for macos

Author: isuruf

runtime/flang/CMakeLists.txt

@@ -512,10 +512,12 @@ add_dependencies(flang_shared flang_static)
 
 target_link_libraries(flang_shared flangrti_shared)
 # Resolve symbols against libm and librt
-if (NOT MSVC)
-  target_link_libraries(flang_shared m rt)
-else()
+if (MSVC)
   set_target_properties(flang_shared PROPERTIES WINDOWS_EXPORT_ALL_SYMBOLS TRUE)
+elseif (APPLE)
+  target_link_libraries(flang_shared m)
+else()
+  target_link_libraries(flang_shared m rt)
 endif()
 
 set(SHARED_LIBRARY FALSE)