Clang's gnu99 mode is not quite the same as GCC's. It will complain
about redefined typedefs being a C11 feature, while GCC does not
complain and allows them in gnu99 mode.
Reviewed-by: NFabiano Fidêncio <fidencio@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>