Comment 12 for bug 1531237

Reviewed: https://review.opencontrail.org/25425
Committed: http://github.org/Juniper/contrail-vrouter/commit/237901ac210cfd7c3e3d11f00c8b86d9d1c96eaa
Submitter: Zuul
Branch: R2.22.x

commit 237901ac210cfd7c3e3d11f00c8b86d9d1c96eaa
Author: Martin Millnert <email address hidden>
Date: Tue Jan 5 19:42:57 2016 +0100

vr_host_interface.c: skb->rxhash renamed in EL7.2

EL7.2 has integrated the upstream (torvalds/linux.git) commit 61b905da33
that renames skbuff's "rxhash" member into "hash".

There are two functions in vr_host_interface.c that relies on the
skb->rxhash member: vr_skb_set_rxhash and vr_skb_get_rxhash.

These two functions already carry tests:
- tests that Linux version is between 2.6.32 and 3.15.0
(skb->rxhash is the correct name in this region)
- tests that, when the above is true, RHEL (major,minor) is at least (6,4)

We're adding another test to declare that when Linux version is greater
than 3.15.0, and:
- a) RHEL (major,minor) is greater than (7,2), use skb->hash,
- b) else, use skb->rxhash.

Compilation of vrouter then succeeds on EL 7.2 again, and sends
packets.

Change-Id: Id70126356293bc08058db10f3ef5005bbd1a1899
Closes-Bug: #1531237
Signed-off-by: Martin Millnert <email address hidden>