fix mbf21 A_ConsumeAmmo taking 0 ammo instead of 1 if ammopershot field not set (need to amend the spec for this, argh)

src/common/engine/namedef.h

@@ -943,6 +943,7 @@ xx(A_FirePlasma)
 xx(A_FireBFG)
 xx(A_FireOldBFG)
 xx(A_FireRailgun)
+xx(A_ConsumeAmmo)
 
 // color channels
 xx(a)

src/gamedata/d_dehacked.cpp

@@ -237,6 +237,7 @@ static AmmoPerAttack AmmoPerAttacks[] = {
 	{ NAME_A_FireBFG, -1},	// uses deh.BFGCells
 	{ NAME_A_FireOldBFG, 1},
 	{ NAME_A_FireRailgun, 1},
+	{ NAME_A_ConsumeAmmo, 1}, // MBF21
 	{ NAME_None, 0}
 };