Currently if we don't exit with $LastExitCode manually,
the cirrus would not report the build/testing failure.

Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210107101919.80-2-luoyonggang@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>