LP#1406867 -- Microsoft Azure Trim fixes

[Andy Whitcroft]

We have reverted the SPC-3 bodges we had (at Microsoft's request) in
Trusty, but this leaves us with no Trim suport there, we retain this fix
in Utopic, but not in Vivid.  On top of that there is now an "official"
fix making its way into v3.20.  Clean up the inconsistancy here and apply
that upstream fix (as sauce for now) to Trusty and later.  This should
leave us with consistant behaviour in all releases which we expect Trim
support to work.

Following this email are two patch kits, the first for trusty consisting
of the new upstream SPC-3 overrides.  The second for utopic which
reverts the original fix we carry and applies the upstream fix.  The two
upstream fixes are identicle, I include both for clarity when applying.
These are already applied to vivid and vivid/unstable.

Proposing for SRU to Trusty and Utopic.

-apw