Fix shieldscale 0 bugs

As stated in the title, this merge request fixes a few bugs relating to setting a player or skin's shieldscale to zero.

Multiplayer CSS when using this wad to set Sonic's default shieldscale to zero.

Before:

After:

NiGHTS Attack using the same wad.

Before:

After:

Using Sol Form as RushChars and then collecting a shield.

Before:

After:

Performing Focus Shift as Espio from ChaotixChars with the Armageddon shield at the start of Deep Sea Zone Act 1 (see the "Frame time" and FPS difference).

Before:

After: