Remove all uses of attribute "unused"

Awesome is built with -Wno-unused-parameter which means there is no point in
explicitly marking arguments as unused.

Signed-off-by: Uli Schlachter <psychon@znc.in>

luaa.c

@@ -62,7 +62,7 @@ extern const struct luaL_reg awesome_screen_meta[];
  * \return The number of elements pushed on stack.
  */
 static int
-luaA_quit(lua_State *L __attribute__ ((unused)))
+luaA_quit(lua_State *L)
 {
     ev_unloop(globalconf.loop, 1);
     return 0;
@@ -89,7 +89,7 @@ luaA_exec(lua_State *L)
 /** Restart awesome.
  */
 static int
-luaA_restart(lua_State *L __attribute__ ((unused)))
+luaA_restart(lua_State *L)
 {
     awesome_restart();
     return 0;