Disable RIOTest route lifetime assert on kernels before 3.13

Also add a small delay after each RIO to give the kernel time to notice
updates before making assertions about routing table state.

Note that bullhead and angler have backported
commit: f104a567e673f382b09542a8dc3500aa689957b4
ipv6: use rt6_get_dflt_router to get default router in rt6_route_rcv

which makes it difficult to predict how earlier kernels will behave.

Bug: 33333670
Test: net_test has now been run on android-msm-angler-3.10 and
android-msm-bullhead-3.10 in addition to android common kernels.

Change-Id: I98fe507e06686af9a2b431735b7e5e554661b280