cmake/LuaHelpers.cmake: check_lua_module: use 'lua -l'

It only shortens the traceback a bit for when a module is not found
though, only removing the "(command line):1: in main chunk" (with
lua5.2).

cmake/LuaHelpers.cmake

@@ -4,7 +4,7 @@
 
 # Check if a module is available in Lua
 function(check_lua_module LUA_PRG_PATH MODULE RESULT_VAR)
-  execute_process(COMMAND ${LUA_PRG_PATH} -e "require('${MODULE}')"
+  execute_process(COMMAND ${LUA_PRG_PATH} -l "${MODULE}" -e ""
     RESULT_VARIABLE module_missing)
   if(module_missing)
     set(${RESULT_VAR} False PARENT_SCOPE)