Fix issue with Hellfire items morphing when transferred to Diablo

[StephenCWills]

Another issue introduced by the complicated hidden requirements of LoadMatchingItems(). The unpacked item must get the CF_HELLFIRE flag from the item regeneration logic instead of the dwBuff field from the packed data. Otherwise, LoadMatchingItems() won't be able to tell if it was unpacked as a Diablo item or a Hellfire item.

devilutionX/Source/loadsave.cpp

Lines 997 to 999 in d92bdd2

	// Ensure that the unpacked item was regenerated using the appropriate
	// game's item generation logic before attempting to use it for validation
	if ((heroItem.dwBuff & CF_HELLFIRE) != (unpackedItem.dwBuff & CF_HELLFIRE)) {

This resolves #7742