Cache interface indices in case interfaces go away.

Without caching them netd will fail to remove rules and routes,
for example, when the Bluetooth reverse-tether interface ("bt-pan")
goes away.

bug:15407087

Change-Id: I99fcf00f9645a0b029455516a705b70110f62ff6
2 files changed
tree: 8490eb9cf8c9f54de243dc1d7787f192bb282f2b
  1. client/
  2. include/
  3. server/