amstream: Return S_FALSE when IMediaSeeking::GetDuration() fails in IAMMultiMediaStream::GetDuration().
Signed-off-by: Gijs Vermeulen <gijsvrm@gmail.com>
Signed-off-by: Zebediah Figura <z.figura12@gmail.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>