add words to deal with void** to contrib/alien

contrib/alien.factor

@@ -9,4 +9,12 @@ dup length "float" <c-array> copy-seq-to-float-array ;
 
 : float-array>array ( byte-array n -- array ) [ swap float-nth ] map-with ;
 
-PROVIDE: contrib/alien ;
+: >void*-array 
+    [ length "void*" <c-array> ] keep
+    dup length [ pick set-char*-nth ] 2each ;
+
+: seq>void*-array ( seq -- seq byte-array )
+    #! output seq is an array of pointers that must be freed
+    [ <malloc-string> ] map dup >void*-array ;
+
+PROVIDE: contrib/alien ;