acl-plugin: match index set to first portrange element if non-first portrange matches...

acl-plugin: match index set to first portrange element if non-first portrange matches on the same hash key (VPP-937)

Multiple portranges that land on the same hash key will always report the match
on the first portrange - even when the subsequent portranges have matched.
Test escape, so make a corresponding test case and fix the code so it passes.

(the commit on stable/1707 has erroneously mentioned VPP-938 jira ticket)

Change-Id: Idbeb8a122252ead2468f5f9dbaf72cf0e8bb78f1
Signed-off-by: Andrew Yourtchenko <ayourtch@gmail.com>
(cherry picked from commit fb088f0a201270e949469c915c529d75ad13353e)
Signed-off-by: Andrew Yourtchenko <ayourtch@gmail.com>