On firing last round of current cannon ammo type, may switch to wrong new ammo type

[Matt Hands]

Happens if player has already selected an alternative ammo type. Game detects cannon is out of current ammo, so performs ToggleRoundType(), but the round type will already have been switched to the player's selected new type (as part of the firing process). So ToggleRoundType() now switches ammo again, resulting in incorrect selection. Bug is in DH 5.1, nothing new.

[Matt Hands]

Fixed in commit 554cfd8.

Now avoids calling unwanted ToggleRoundType() on running out of ammo, if the player has already selected a different PendingProjectileType.