Adds the new health analyser noises to PDA scanners and mech scanners (#14860)

code/modules/modular_computers/computers/modular_computer/variables.dm

@@ -25,6 +25,7 @@
 	var/pAI_lock = FALSE									// Toggles whether pAI can interact with the modular computer while installed in it
 	var/obj/item/card/id/registered_id = null 				// ID used for chat client registering
 	var/scan_mode = null									// Mode used for health/reagent scanners
+	var/last_scan = 0										// Used for the PDA analyser spam detection
 	var/silent = FALSE
 	var/doorcode = "smindicate"
 	var/hidden = FALSE