Remove include userdefs.h where not needed

@@ -31,11 +31,10 @@
  */
 
 #include <errno.h>
 #include <sys/types.h>
 #include <stdio.h>
-#include <userdefs.h>
 #include <grp.h>
 #include <libcmdutils.h>
 
 static int findunusedgid(gid_t start, gid_t stop, gid_t *ret);
 static boolean_t isreservedgid(gid_t gid);