buildroot

fio: add upstream patch to fix build on SuperH

Upstream was super reactive, and already committed a patch to fix the
build on SuperH, so we take this upstream patch in Buildroot and
re-enable fio on SuperH.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>