Duke 3D & RR: Repair issue where player would not return to centre following hard landing.

- Accidentally left in while merging changes from upstream.
- Change restores accuracy to game play in that a hard landing now returns the player's view to center.

source/duke3d/src/player.cpp

@@ -5301,7 +5301,6 @@ void P_ProcessInput(int playerNum)
                             A_PlaySound(DUKE_LAND, pPlayer->i);
 #endif
                     }
-                    pPlayer->on_ground = 1;
                 }
                 else
                     pPlayer->on_ground = 0;

source/rr/src/player.cpp

@@ -8051,7 +8051,6 @@ check_enemy_sprite:
                             pPlayer->moto_turb = 12;
                         }
                     }
-                    pPlayer->on_ground = 1;
                 }
                 else
                     pPlayer->on_ground = 0;