Wait for IpClient to shutdown

This makes sure that we never accidentally have two IpClients vying
for control of the same interface.

Test: as follows
    - built
    - flashed
    - booted
Bug: 62476366
Change-Id: Iab4ca7c2445e70b6f8beaf5dc6921cb0c6cd56ed
1 file changed
tree: 16e8f4802e5e638359a468213486bfffd18aab3f
  1. service-t/
  2. Android.mk