Implement root-less ICMP for InetAddress#isReachable

IPPROTO_ICMP socket kind allows sending and receiving ICMP Echo
messages without priviledges.

Test: libcore.java.net.InetAddressTest
Bug: 31926888
Bug: http://code.google.com/p/android/issues/detail?id=20106
Change-Id: I97e908695a3e04ac11841acbe2c887f26e6b8910
8 files changed