Exit with EXIT_SUCCESS/EXIT_FAILURE instead of 0 and 1

Fixed for consistency purposes.

env.c

@@ -35,7 +35,7 @@ main(int argc, char **argv)
 	while(environ && *environ)
 		printf("%s\n", *environ++);
 
-	return 0;
+	return EXIT_SUCCESS;
 }
 
 void