[v2.2.10] MobjDamage hooks don't work right in non-NiGHTS special stages

[Tarregor]

Of course, by non-NiGHTS Special Stages, I mean the same type that vanilla SRB2's multiplayer special stages are.

MobjDamage hooks for MT_PLAYER will never trigger, seemingly under all circumstances. Similarly might be so for ShouldDamage hooks, to at least a limited extent.