fix TokuDB not to build ft-index library when disabled

storage/tokudb/CMakeLists.txt

@@ -9,7 +9,7 @@ int main() { return 0; }
 " TOKUDB_OK)
 ENDIF()
 
-IF(NOT TOKUDB_OK OR WITHOUT_TOKUDB OR WITHOUT_TOKUDB_STORAGE_ENGINE)
+IF(NOT TOKUDB_OK OR PLUGIN_TOKUDB STREQUAL "NO")
   MYSQL_ADD_PLUGIN(tokudb DISABLED)
   RETURN()
 ENDIF()