Fix player 1 controls affecting others in player selection

[Kurtsley]

Fixes #855

Prevents player one's controls from affecting other players in the player selection menu.

See comment: https://github.com/cxong/cdogs-sdl/issues/855#issuecomment-2166611821

[Kurtsley]

So by checking if useMenuCmd returns more than 1 here, as per the suggestion, it essentially disables the default menu commands for all menus that have multiple players ex: equip menu. The default commands seem to work in all other menus. This functionality looks to be supported as the text at the bottom of most menus shows the default controls, but it switches to the mapped controls in the player select screen.