Linux 3.18 rc6

Steady progress towards final release, although we still have a big
unknown worry in a regression that Dave Jones reported and that we
haven't solved yet. In the process of chasing that one down, there's
been a fair amount of looking at various low-level details, and that
found some dubious issues, but no smoking gun yet. But that explains
some of the patches in rc6..

The good news is that things are generally calming down, and most of
the changes are smallish regression fixes here, with a smattering of
stable patches. About half drivers (networking, sound, pci,
infiniband, etc), with architecture updates (x86, mips, arm), and
networking code being about half of the rest. And the last quarter is
"misc": filesystem fixes, documentation, scheduler..

Really not a whole lot of code changed, and if it wasn't for the
pending trouble from DaveJ, I'd probably be perfectly happy. Let's see
how that all unfolds, but in the meantime, the more testing this can
get, the better.

So go out and give it a good shake-down,