drivers/net: macvtap and tun depend on INET

These drivers now call ipv6_proxy_select_ident(), which is defined
only if CONFIG_INET is enabled.  However, they have really depended
on CONFIG_INET for as long as they have allowed sending GSO packets
from userland.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Fixes: f43798c276 ("tun: Allow GSO using virtio_net_hdr")
Fixes: b9fb9ee07e ("macvtap: add GSO/csum offload support")
Fixes: 5188cd44c5 ("drivers/net, ipv6: Select IPv6 fragment idents for virtio UFO packets")
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/Kconfig

@@ -135,6 +135,7 @@ config MACVLAN
 config MACVTAP
 	tristate "MAC-VLAN based tap driver"
 	depends on MACVLAN
+	depends on INET
 	help
 	  This adds a specialized tap character device driver that is based
 	  on the MAC-VLAN network interface, called macvtap. A macvtap device
@@ -200,6 +201,7 @@ config RIONET_RX_SIZE
 
 config TUN
 	tristate "Universal TUN/TAP device driver support"
+	depends on INET
 	select CRC32
 	---help---
 	  TUN/TAP provides packet reception and transmission for user space