Update our copy of the Linux headers to upstream 4.17-rc6
(kernel commit 771c577c23bac90597c68).
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20180525132755.21839-6-peter.maydell@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>