Remove empty? interface

empty? is now defined as an interface in Carp's core library, so we no
longer need the definition provided here.

Author: scolsen

src/size.carp

@@ -47,4 +47,3 @@
 ;; Generic interfaces for sized types
 (definterface len (Fn [(Ref (f n a))] Int))
 (definterface replicate (Fn [a] (f n a)))
-(definterface empty? (Fn [(Ref (f n a))] Bool))