I've just installed gcc-6.0 to see what kinds of new warnings
we get. It turns out that it's actually really useful once I
disabled -Wunused-const-variable, and all of the warnings it
found in network drivers seem valid.
Sorry for the bad timing in the merge window, but I figured
it would be better to send the fixes as I found the bugs
rather than waiting for the next cycle. The first three
look appropriate for stable backports.
The other two only fix a gcc warning about incorrect whitespace,
probably not worth backporting those.
Arnd
