[tcpconnect] filter traced connection based on destination ports

[tcpconnect] filter traced connection based on destination ports

Test:
While running:
while [ 1 ]; do nc -w 1 100.127.0.1 80; nc -w 1 100.127.0.1 81; done

root@vagrant:/mnt/bcc# ./tools/tcpconnect.py
PID    COMM         IP SADDR            DADDR            DPORT
19978  nc           4  10.0.2.15        100.127.0.1      80
19979  nc           4  10.0.2.15        100.127.0.1      81
19980  nc           4  10.0.2.15        100.127.0.1      80
19981  nc           4  10.0.2.15        100.127.0.1      81
root@vagrant:/mnt/bcc# ./tools/tcpconnect.py  -P 80
PID    COMM         IP SADDR            DADDR            DPORT
19987  nc           4  10.0.2.15        100.127.0.1      80
19989  nc           4  10.0.2.15        100.127.0.1      80
19991  nc           4  10.0.2.15        100.127.0.1      80
19993  nc           4  10.0.2.15        100.127.0.1      80
19995  nc           4  10.0.2.15        100.127.0.1      80
root@vagrant:/mnt/bcc# ./tools/tcpconnect.py  -P 80,81
PID    COMM         IP SADDR            DADDR            DPORT
8725   nc           4  10.0.2.15        100.127.0.1      80
8726   nc           4  10.0.2.15        100.127.0.1      81
8727   nc           4  10.0.2.15        100.127.0.1      80
8728   nc           4  10.0.2.15        100.127.0.1      81
8729   nc           4  10.0.2.15        100.127.0.1      80

Fixes #681