salamanders have no legs

However, they could ride.  Marilith is similar, but since it's MZ_LARGE,
that check disallowed riding.  Added a check for slithy(), like
canwearobj() already has.

doc/fixes34.1

@@ -299,6 +299,7 @@ vault wall repair should remove traps subsequently created at affected spots
 don't reveal deity name when a high priest(ess) gives temple entry greeting
 for ordinary remove curse, don't uncurse quivered object unless it is suitable
 	to be used as a quivered weapon (ammo or missile)
+salamanders have no legs and cannot ride
 
 
 Platform- and/or Interface-Specific Fixes