Use a UDP socket instead of a ping socket for ioctls.

The type of socket used for ioctls does not affect the success
of the calls themselves, so UDP is just as good as ping.
However, UDP makes this code more reusable, because on many
systems, ping sockets are restricted by default.

Test: all_tests.sh passes on android-4.9
Change-Id: I44a25af880659b364edbec72850d968b2ef17f11