tree dac0fc6b9a4fbe38693146ab998a0f1e3da58c64
parent d2d05940681fe3ca960638c924e886474c77ed69
author William A. Kennington III <wak@google.com> 1549084030 -0800
committer William A. Kennington III <wak@google.com> 1550175012 -0800

ethernet_interface: Only write Gateway= lines when present

This doesn't affect the total system behavior but it cleans up error
output from systemd-networkd which doesn't like empty Gateway= lines
when we don't have a set gateway.

Tested:
    Set the system to a static configuration with no gateway configured
    and saw that the line was no longer written. Configured a gateway
    and the line is written as expected.

Change-Id: I1ff9c4f564fab54d0c54e3f87fcd50b623f0fbda
Signed-off-by: William A. Kennington III <wak@google.com>