wrlib: added support for imagemagick third-party lib

It uses to provide some missing common image format
like SVG, BMP, PICT, ...

src/main.c

@@ -201,6 +201,7 @@ noreturn void Exit(int status)
 	if (dpy)
 		XCloseDisplay(dpy);
 
+	RShutdown(); /* wrlib clean exit */
 	wutil_shutdown();  /* WUtil clean-up */
 
 	exit(status);