Prevent per unitdef weapons counter limiting the number of possible unitdefs

[lostsquirrel1]

Make udWeaponCounts length set to unit def count rather than a fix length.

The passing of unitDefHandler as an argument (rather than globally) is to clearly show that there is a dependency in the initialization order.

[sprunk]

Is the array even useful? It seems to only ever be used here

RecoilEngine/rts/Sim/Weapons/WeaponLoader.cpp

Lines 52 to 53 in 3d105ef

	if ((n = udWeaponCounts.at(unitDef->id)) > MAX_WEAPONS_PER_UNIT)
	n = (udWeaponCounts.at(unitDef->id) = unitDef->NumWeapons());

so the weapon count could just be cached in the unit def itself.

That said, that would be a bit of a rewrite to this looks good too.