acl: implement counters

acl: implement counters

implement per-acl-number counters in the stats segment.
They are created during the ACL creation,
the counters are incremented in the dataplane using
the new inline function with the extra parameter being
the packet size. Counting in shared segment adds
a noticeable overhead, so add also an API to
turn the counters on.

Type: feature

Change-Id: I8af7b0c31a3d986b68089eb52452aed45df66c7b
Signed-off-by: Andrew Yourtchenko <ayourtch@gmail.com>