Keep Gerrit ACL lines deduplicated
Keep Gerrit ACL lines deduplicated

Gerrit ACLs can have multiple duplicate option keys in a section,
but completely duplicate lines (key and value together) have no use
so make sure they're collapsed into at most 1 copy.

Change-Id: I6bf43e860dcc8c3d7b2846d4e058b6c8ac7243eb

dongwenjuan/project-config,openstack-infra/project-config,openstack-infra/project-config,dongwenjuan/project-config,Tesora/tesora-project-config,noorul/os-project-config,Tesora/tesora-project-config,noorul/os-project-config