Test variable is not already free before freeing.

src/cd-info.c

@@ -1,5 +1,5 @@
 /*
-    $Id: cd-info.c,v 1.62 2004/05/16 13:33:40 rocky Exp $
+    $Id: cd-info.c,v 1.63 2004/05/24 23:28:05 rocky Exp $
 
     Copyright (C) 2003, 2004 Rocky Bernstein <rocky@panix.com>
     Copyright (C) 1996, 1997, 1998  Gerd Knorr <kraxel@bytesex.org>
@@ -865,7 +865,7 @@ main(int argc, const char *argv[])
       }
     }
     cdio_free_device_list(device_list);
-    free(device_list);
+    if (device_list) free(device_list);
   }
 
   first_track_num = cdio_get_first_track_num(cdio);