tc_util: support TCA_STATS_PKT64 attribute

tc_util: support TCA_STATS_PKT64 attribute

Kernel exports 64bit packet counters for qdisc/class stats in linux-5.5

Tested:

$ tc -s -d qd sh dev eth1 | grep pkt
 Sent 4041158922097 bytes 46393862190 pkt (dropped 0, overlimits 0 requeues 2072)
 Sent 501362903764 bytes 5762621697 pkt (dropped 0, overlimits 0 requeues 247)
 Sent 533282357858 bytes 6128246542 pkt (dropped 0, overlimits 0 requeues 329)
 Sent 515878280709 bytes 5875638916 pkt (dropped 0, overlimits 0 requeues 267)
 Sent 516221011694 bytes 5933395197 pkt (dropped 0, overlimits 0 requeues 258)
 Sent 513175109761 bytes 5898402114 pkt (dropped 0, overlimits 0 requeues 231)
 Sent 480207942964 bytes 5519535407 pkt (dropped 0, overlimits 0 requeues 229)
 Sent 483111196765 bytes 5552917950 pkt (dropped 0, overlimits 0 requeues 240)
 Sent 497920120322 bytes 5723104387 pkt (dropped 0, overlimits 0 requeues 271)
$ tc -s -d cl sh dev eth1 | grep pkt
 Sent 513196316238 bytes 5898645862 pkt (dropped 0, overlimits 0 requeues 231)
 Sent 533304444981 bytes 6128500406 pkt (dropped 0, overlimits 0 requeues 329)
 Sent 480227709687 bytes 5519762597 pkt (dropped 0, overlimits 0 requeues 229)
 Sent 501383660279 bytes 5762860276 pkt (dropped 0, overlimits 0 requeues 247)
 Sent 483131168192 bytes 5553147506 pkt (dropped 0, overlimits 0 requeues 240)
 Sent 515899485505 bytes 5875882649 pkt (dropped 0, overlimits 0 requeues 267)
 Sent 497940747031 bytes 5723341475 pkt (dropped 0, overlimits 0 requeues 271)
 Sent 516242376893 bytes 5933640774 pkt (dropped 0, overlimits 0 requeues 258)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>