fix lua plugin linker error

lua/CMakeLists.txt

@@ -5,6 +5,7 @@ PROJECT(uci C)
 SET(CMAKE_INSTALL_PREFIX /)
 
 ADD_DEFINITIONS(-Os -Wall -Werror --std=gnu99 -g3 -I..)
+LINK_DIRECTORIES(${CMAKE_CURRENT_SOURCE_DIR}/..)
 
 IF(APPLE)
 	SET(CMAKE_SHARED_MODULE_CREATE_C_FLAGS "${CMAKE_SHARED_MODULE_CREATE_C_FLAGS} -undefined dynamic_lookup")