Common - Fix `CBA_fnc_canAddItem` when item mass is 0

[PabstMirror]

for massless items, func would return true e.g.

player addBackpack "B_Respawn_Sleeping_bag_brown_F";
[player, "ACE_dogtag_1", 1, false, false, true] call CBA_fnc_canAddItem

or trying to add to static-weapons