Most of these fixes appear to be harmless and should never occur.
However, there were a few cases in this patch which do concern me,
I doubt we're seeing them but they look possible... mainly in the
user tools.
compile option. In most case the variables are only unused when
debugging is disabled (ASSERT) however they do waste stack if that
case if the compiler doesn't optimize it out (it should). But more
importantly disabling this warning prevent us from noticing legit
unused variables accidentally left in other place of the code.
Brian Behlendorf