allow ammo metals

- brass, lead and platinum can be used as ammo

There are some kinds of ammo that you can create, but cannot assign to
squads because the materials are missing the [ITEMS_AMMO] tag. I've
updated the ones I found to be missing, but there may be more.

Dwarf Fortress/raw/objects/inorganic_stone_mineral.txt

@@ -376,6 +376,7 @@ you can make a lighter colored bronze by adding bismuth, used temp values from b
 	[SPEC_HEAT:377]
 	[MELTING_POINT:11656]
 	[BOILING_POINT:14068]
+	[ITEMS_AMMO]
 	[SOLID_DENSITY:8550]
 	[LIQUID_DENSITY:8000]
 	[MOLAR_MASS:64000]
@@ -792,6 +793,7 @@ you can make a lighter colored bronze by adding bismuth, used temp values from b
 	[SPEC_HEAT:130]
 	[MELTING_POINT:10589]
 	[BOILING_POINT:13148]
+	[ITEMS_AMMO]
 	[SOLID_DENSITY:11340]
 	[LIQUID_DENSITY:10660]
 	[MOLAR_MASS:207200]
@@ -1077,6 +1079,7 @@ you can make a lighter colored bronze by adding bismuth, used temp values from b
 	[SPEC_HEAT:130]
 	[MELTING_POINT:13182]
 	[BOILING_POINT:16885]
+	[ITEMS_AMMO]
 	[SOLID_DENSITY:21400]
 	[LIQUID_DENSITY:19770]
 	[MOLAR_MASS:195084]