Improve parallelism between bgp/xmpp state machine and io tasks

[Nischal Sheth]

Current implementation has a couple of limitations:

1. All xmpp::StateMachine and io::Reader tasks for xmpp use instance 0.
This means that only a single xmpp::StateMachine task can run at a time
and no io::Reader task for xmpp can run in parallel with it.

2. Blanket exclusion between bgp/xmpp::StateMachine and io::Reader tasks.
This means that, even if 1 above is fixed, an xmpp:StateMachine task and
an io::Reader task for different xmpp sessions cannot run in parallel.
Same applies to bgp::StateMachine and io::Reader tasks for different bgp sessions.

[OpenContrail Admin (ci-admin-f)]

Review in progress for https://review.opencontrail.org/19168
Submitter: Nischal Sheth (<email address hidden>)

[OpenContrail Admin (ci-admin-f)]

Reviewed: https://review.opencontrail.org/19168
Committed: http://github.org/Juniper/contrail-controller/commit/42551a2e6124f112d941f9f18e90f8cf67054392
Submitter: Zuul
Branch: master

commit 42551a2e6124f112d941f9f18e90f8cf67054392
Author: Nischal Sheth <email address hidden>
Date: Mon Mar 28 10:48:30 2016 -0700

Improve parallelism between bgp/xmpp state machine and io tasks

Highlights:

- Set task_instance for xmpp::StateMachine based on remote ip address
- Set task_instance for xmpp io::Reader to be same as xmpp::StateMachine
- Remove blanket exclusion between io::Reader and xmpp::StateMachine
- Make io::Reader and xmpp::StateMachine exclusive for same task_instance
- Remove blanket exclusion between io::Reader and bgp::StateMachine
- Make io::Reader and bgp::StateMachine exclusive for same task_instance
- Limit max task_instance for above tasks to scheduler's thread count
- Add concurrency annotations to PeerRibMembershipManager
- Fix concurrency issues in PeerRibMembershipManager
- Fix concurrency issues in BgpXmppChannelManager

Change-Id: I96ff21fe7da06cd37a057d53712f85511dd8ff2a
Closes-Bug: 1566149