Revert "[MIRROR] Replace all secondary flags with bitflags stored in the flags_2 var" (#2457)

ok you know what yeah i think i'll properly mirror https://github.com/Citadel-Station-13/Citadel-Station-13/pull/2411

code/game/objects/objs.dm

@@ -58,7 +58,7 @@
 
 /obj/throw_at(atom/target, range, speed, mob/thrower, spin=1, diagonals_first = 0, datum/callback/callback)
 	..()
-	if(flags_2 & FROZEN_2)
+	if(HAS_SECONDARY_FLAG(src, FROZEN))
 		visible_message("<span class='danger'>[src] shatters into a million pieces!</span>")
 		qdel(src)