Suppress NewApi warnings for @SystemApi -> public APIs

Android Lint doesn't handle API change from @SystemApi to public API
correctly (see b/193460475). We have to manually suppress those
warnings for now.

This CL suppresses warnings related to these APIs:
 - IpPrefix(InetAddress, int)
 - RouteInfo#getType

Bug: 186082280
Test: presubmit
Change-Id: Ib12f5ab39dfad10d3b367ad6f49a74df4f112211