net block: get_default_interface in netlink.rs can not detect wwan0

[cjacker]

My thinkpad has a xmm7360 4g module, after it connected to internet, i3status-rust can not detect it as default interface.

After adding some println! to netlink.rs and get the output as:

All interfaces:
lo, index:1
enp0s31f6, index:2
wlan0, index:4
wwan0, index:15

get_default_interface: 4

route -n:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         0.0.0.0         0.0.0.0         U     1000   0        0 wwan0
0.0.0.0         192.168.2.1     0.0.0.0         UG    3004   0        0 wlan0
192.168.2.0     0.0.0.0         255.255.255.0   U     3004   0        0 wlan0

ip route show default:

default dev wwan0 proto static metric 1000
default via 192.168.2.1 dev wlan0 proto dhcp src 192.168.2.148 metric 3004

ip route get 8.8.8.8:

8.8.8.8 dev wwan0 src 10.225.190.236 uid 1000