Replace hp checks with IsBattlerAlive

[ghoulslash]

Can't find an issue number, but this fixes Toxic/Flame Orb from activating on fainted battlers.

Also updated a bunch of .hp != 0 --> IsBattlerAlive and .hp == 0 to !IsBattlerAlive while I was at it

[AlexOn1ine]

I wasn't able to repro the toxic / flame orb bug and it seems there is already a check when ItemBattleEffects is called.

        case ENDTURN_ORBS:
            if (IsBattlerAlive(battler) && ItemBattleEffects(ITEMEFFECT_ORBS, battler, FALSE))
                effect++;
            gBattleStruct->turnEffectsTracker++;
            break;

So the second check is redundant.

/Edit: Ghoul you fixed it yourself in #2585 😅

[ghoulslash]

I wasn't able to repro the toxic / flame orb bug and it seems there is already a check when ItemBattleEffects is called.

        case ENDTURN_ORBS:
            if (IsBattlerAlive(battler) && ItemBattleEffects(ITEMEFFECT_ORBS, battler, FALSE))
                effect++;
            gBattleStruct->turnEffectsTracker++;
            break;

So the second check is redundant.

/Edit: Ghoul you fixed it yourself in #2585 😅

lol that's funny. oops. Just removed the redundant checks

[AlexOn1ine]

I think this one isn't needed as well.