Added luajit interp lines to the other 2 lua examples.

examples/lua/sorting.lua

@@ -1,3 +1,4 @@
+#!/usr/bin/env luajit
 fruits = {"banana","orange","apple","grapes"}
 
 for k,v in ipairs(fruits) do

examples/lua/symmetric_difference.lua

@@ -1,3 +1,4 @@
+#!/usr/bin/env luajit
 A = { ["John"] = true, ["Bob"] = true, ["Mary"] = true, ["Elena"] = true }
 B = { ["Jim"] = true, ["Mary"] = true, ["John"] = true, ["Bob"] = true }