fix SUNITDMG_ApplyResistancesAndAbsorb when dealing with negative damage values

[nooperation]

In the original codebase SUNITDMG_ApplyResistancesAndAbsorb sets the damage value to 0 and returns early if pValue is <= 0;

This matters for weird cases where you have 0 damage and some additional absorbs/etc, pushing pValue negative when the original logic would not have done that