Fix build dependency.

Recreate mysql_sys_schema.sql, whenever one of its source files changes.

scripts/sys_schema/CMakeLists.txt

@@ -167,6 +167,7 @@ SET(files
   ${CMAKE_CURRENT_SOURCE_DIR}/after_setup.sql)
 ENDIF()
 
+SET_PROPERTY(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS ${files})
 SET(CMAKE_CONFIGURABLE_FILE_CONTENT)
 
 FOREACH(f ${files})