Fix #3920 CL: 1. Parse the TCP metrics header in `/proc/net/snmp` to get the right position of the metrics. 2. Add 2 new metrics: `tcp_in_segs` and `tcp_out_segs`
Fix #3920 CL: 1. Parse the TCP metrics header in `/proc/net/snmp` to get the right position of the metrics. 2. Add 2 new metrics: `tcp_in_segs` and `tcp_out_segs`