video: decoder: vda: use wrapping multiplication for timestamp
video: decoder: vda: use wrapping multiplication for timestamp

When decoding using libvda, the frame timestamp is truncated to 32-bits
and needs to be restored to its original value. This is done by doing a
multiplication with the truncation factor. However, if libvda gives us
an invalid timestamp, the multiplication can overflow and cause the
video device process to panic. Avoid this by switching to a wrapping
multiplication - the passed timestamp will still be invalid, but the
decoder device will signal an error instead of crashing.

BUG=None
TEST=cargo build --features "video-decoder,libvda"

Change-Id: Iabe683a997e0e9dea8c2bea53ef520f53868e590
Reviewed-on: https://chromium-review.googlesource.com/c/crosvm/crosvm/+/3958881
Reviewed-by: David Stevens <2f87ba95ff5d327328bd68c2e86a4d9f2ba99bd0@chromium.org>
Commit-Queue: Alexandre Courbot <301cd6a3ea50a894b4b51e385c5eb12b9a4ffc0c@chromium.org>

google/crosvm,google/crosvm,google/crosvm,google/crosvm