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/_onclick/hud/screen_objects.dm

@@ -258,7 +258,7 @@
 				var/obj/item/clothing/mask/M = C.wear_mask
 				if(M.mask_adjusted) // if mask on face but pushed down
 					M.adjustmask(C) // adjust it back
-				if( !(M.flags_1 & MASKINTERNALS_1) )
+				if( !(M.flags & MASKINTERNALS) )
 					to_chat(C, "<span class='warning'>You are not wearing an internals mask!</span>")
 					return