Changes the value of the guard.dist parameter for the player's current HitDef. The guard.dist is the x-distance from P1 in which P2 will go into a guard state if P2 is holding the direction away from P1. If P1 currently has no active HitDef, then AttackDist has no effect.

Required parameters:

- value = guard_dist (int)
  New guard distance, in pixels.

Optional parameters:

- none

Example:

`none`