No popup appears when prioritizing a non-violent colonist to a mortar

[Jimyoda]

For all version thru A18.
Perhaps just WAD, but in case it's an oversight and not actually intentional...

There's no popup when trying to man a mortar if the pawn is incapable of violence.

This is inconsistent with how a "incapable of violence" popup appears when trying to do anything else violent:
- pick up a weapon
- attack a structure
- melee a pawn
- slaughter an animal

[ison]

Added (though not for A18), thanks.