Use the standard FindLua.cmake instead of the modified bundled FindLUA.cmake,
and force the use of an exact Lua version.

--- a/source/glest_game/CMakeLists.txt
+++ b/source/glest_game/CMakeLists.txt
@@ -64,7 +64,7 @@
 		ENDIF()
 	ENDIF()
 
-	FIND_PACKAGE(LUA REQUIRED)
+	FIND_PACKAGE(Lua ${FORCE_LUA_VERSION} EXACT REQUIRED)
 	INCLUDE_DIRECTORIES(${LUA_INCLUDE_DIR})
 	IF(UNIX)
 		SET(EXTERNAL_LIBS ${EXTERNAL_LIBS} ${LUA_LIBRARIES})
--- a/source/shared_lib/CMakeLists.txt
+++ b/source/shared_lib/CMakeLists.txt
@@ -132,7 +132,7 @@
 		SET(EXTERNAL_LIBS ${EXTERNAL_LIBS} ${OPENAL_LIBRARY})
 	ENDIF()
 
-        FIND_PACKAGE(LUA REQUIRED)
+        FIND_PACKAGE(Lua ${FORCE_LUA_VERSION} EXACT REQUIRED)
         INCLUDE_DIRECTORIES(${LUA_INCLUDE_DIR})
         IF(UNIX)
 	        SET(EXTERNAL_LIBS ${EXTERNAL_LIBS} ${LUA_LIBRARIES} ${CMAKE_DL_LIBS})