qemu-iotests: flush after every test

This makes it possible to see what is happening, even if the output of
"make check-block" is not sent to a tty (for example if it is sent to
grep or tee).

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 file changed