Mortar turret ammo selection dropdown is empty

[SuperStucco]

In the attached 49.12 save, there is a mortar turret. When customizing, the ammo type dropdown is completely blank:

The game date is 3010, so the only ammo type currently available is the standard shaped charge. But there should still be something in the dropdown as a single selectable item rather than leaving it blank.

Mortar_turret_ammo.sav.gz

[neoancient]

The 'Mech Mortar is extinct between 2819 and 3043, so no ammo is available. I submitted a fix that adds an option to ignore extinction dates in configuring equipment.