Merge branch 'review/pause-stats-v3' into master

Jakub Kicinski:

This set adds support for pause frame statistics.

First pause frame info is extended to support --json.

Pause stats are first of this kind of statistics so add
support for a new flag (--include-statistics).

Next add support for dumping policy to check if the statistics
flag is supported for a given subcommand.

Last but not least - display statistics.

v3:
 - rename the ctx variable to policy_ctx
 - instead of returning the flags policy save it to a member
   of struct nl_context, for potential reuse. Also we don't
   have to worry about returning flags and negative errors
   from the read helper this way :)