There is a hack to add "-lrt" to the output from "mysql_config --lib_r",

kboortz · kboortz · commit 900e1286c468 · 2013-08-14T12:37:27.000+02:00
likely to compensate for a bug in "mysql_config" in some releases.

Changed so it doesn't add "-lrt" on OS X where is no "librt".
diff --git a/FindMySQL.cmake b/FindMySQL.cmake
@@ -225,7 +225,9 @@ ELSE (WIN32)
     IF (MYSQLCLIENT_STATIC_LINKING)
       _MYSQL_CONFIG_REPLACE(MYSQL_LIBRARIES 
              "mysqlclient(_r| |$)" "${MYSQL_LIB}" "(^| )-l" "--libs_r")
-       LIST(APPEND MYSQL_LIBRARIES "rt")
+      IF (NOT ${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
+        LIST(APPEND MYSQL_LIBRARIES "rt")
+      ENDIF ()
     ELSE (MYSQLCLIENT_STATIC_LINKING)
       _MYSQL_CONFIG(MYSQL_LIBRARIES "(^| )-l" "--libs_r")
     ENDIF (MYSQLCLIENT_STATIC_LINKING)
