ip: Fix batch processing

After the comment cited below, batch mode neglects to set the global
variable batch_mode to a non-zero value. Netns and VRF commands use this
variable, and break in batch mode. Fix by setting the value again.

Fixes: 1d9a81b8c9 ("Unify batch processing across tools")
Reported-by: Tim Rice <trice@posteo.net>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

ip/ip.c

@@ -156,6 +156,7 @@ static int batch(const char *name)
 		return EXIT_FAILURE;
 	}
 
+	batch_mode = 1;
 	ret = do_batch(name, force, ip_batch_cmd, &orig_family);
 
 	rtnl_close(&rth);