TcpSocketMonitor code hardening

This patch adds a couple of additional guards to make TcpSocketMonitor
more robust:
  - TcpSocketMonitor::updateSocketStats() is not called if the Netlink
  message type does not match SOCK_DIAG_BY_FAMILY
  - the tcpinfo_get macro now correctly takes into account the length of
  the field that is accessed when comparing to the number of bytes
  available for struct tcp_info.

In additional, tcpi_data_segs_out which is not available on 4.4 kernels
is replaced by tcpi_segs_out.

Bug: 64147860, 72512637
Test: manual tests
Change-Id: I898fc07362788b7991594d303665a88f57bf1b35