Vrouter agent - VRF Delete timeouts crash needs to have better debug ability

[Prabhjot Singh Sethi]

when a VRF delete timeout crash happens in a scaled scenario debugging the reason for the same becomes very difficult.

need a mechanism to track back references to get a clear picture on the objects referring to a particular VRF.

[OpenContrail Admin (ci-admin-f)]

Review in progress for https://review.opencontrail.org/13055
Submitter: Prabhjot Singh Sethi (<email address hidden>)

[OpenContrail Admin (ci-admin-f)]

Reviewed: https://review.opencontrail.org/13055
Committed: http://github.org/Juniper/contrail-controller/commit/a0716c768ac1d21296133a0bd7c1d57784f956a6
Submitter: Zuul
Branch: master

commit a0716c768ac1d21296133a0bd7c1d57784f956a6
Author: Prabhjot Singh Sethi <email address hidden>
Date: Fri Aug 14 11:27:52 2015 +0530

Intrusive pointer back reference infra

Changes to introduce intrusive pointer back reference
infra to manage back reference pointers of the objects
hold intrusive pointer reference.
incorporating use of this infra for VRF intrusive ptr
references to have better debug ability for VRF delete
timeout crash

Change-Id: I10d27af5a1f86067279ef788a8c99003dbc989f0
Closes-Bug: 1484796

[OpenContrail Admin (ci-admin-f)]

Review in progress for https://review.opencontrail.org/14333
Submitter: Prabhjot Singh Sethi (<email address hidden>)

[OpenContrail Admin (ci-admin-f)]

Review in progress for https://review.opencontrail.org/17031
Submitter: Hari Prasad Killi (<email address hidden>)

[Prabhjot Singh Sethi (prabhjot)]

check-ed in gdb python macros(bug-1573419) to find db entries hold reference to vrf entry for ease of debugging, will avoid this change backport