lua: LuaPushStringBuffer optimization

Only use a temp buffer when really necessary, which is when the
buffer size is not a multiple of 4.

src/util-lua.c

@@ -236,6 +236,7 @@ void LuaPrintStack(lua_State *state) {
 
 int LuaPushStringBuffer(lua_State *luastate, const uint8_t *input, size_t input_len)
 {
+    if (input_len % 4 != 0) {
         /* we're using a buffer sized at a multiple of 4 as lua_pushlstring generates
          * invalid read errors in valgrind otherwise. Adding in a nul to be sure.
          *
@@ -248,6 +249,9 @@ int LuaPushStringBuffer(lua_State *luastate, const uint8_t *input, size_t input_
 
         /* return value through luastate, as a luastring */
         lua_pushlstring(luastate, (char *)buf, input_len);
+    } else {
+        lua_pushlstring(luastate, (char *)input, input_len);
+    }
     return 1;
 }