Disable object storage devices for now.

Until we crack the problem of writing/reading to S3 using the droplet
library disable the use of these kind of devices.

src/stored/backends/object_store_device.c

@@ -91,6 +91,11 @@ int object_store_device::d_open(const char *pathname, int flags, int mode)
    dpl_vfile_flag_t dpl_flags;
    dpl_option_t dpl_options;
 
+#if 1
+   Mmsg1(errmsg, _("Object Storage devices are not yet supported, please disable %s\n"), dev_name);
+   return -1;
+#endif
+
    /*
     * Initialize the droplet library when its not done previously.
     */