Fixes 2647 (shiptest-ss13#2648)

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## About The Pull Request

Arcane machine tried to smelt up to 10 sheets of material but the alloy
smelting proc didn't get a smelting number passed so it just spawned 1
sheet and called it a day.

## Why It's Good For The Game

fixes shiptest-ss13#2647

## Changelog

:cl:
fix: ore smelter no longer obliterates materials when smelting alloys
/:cl:

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Signed-off-by: Theos <[email protected]>

code/modules/mining/machine_processing.dm

@@ -253,7 +253,7 @@
 	var/datum/component/material_container/materials = GetComponent(/datum/component/material_container)
 	materials.use_materials(alloy.materials, amount)
 
-	generate_mineral(alloy.build_path)
+	generate_mineral(alloy.build_path, amount)
 
 /obj/machinery/mineral/processing_unit/proc/can_smelt(datum/design/D)
 	if(D.make_reagents.len)
@@ -271,8 +271,8 @@
 
 	return build_amount
 
-/obj/machinery/mineral/processing_unit/proc/generate_mineral(P)
-	var/O = new P(src)
+/obj/machinery/mineral/processing_unit/proc/generate_mineral(P, amount)
+	var/O = new P(src, amount)
 	unload_mineral(O)
 
 /obj/machinery/mineral/processing_unit/on_deconstruction()