video: avoid overflows when doing int operations for size

size is a gsize, so cast the operands to it to avoid overflows
and setting wrong value to the video size.

Includes tests.

https://bugzilla.gnome.org/show_bug.cgi?id=731195
videoscale: vs_image: strides are a gsize

The strides that are set from the GstVideoInfo structs are
a gsize. Using an int can cause overflows when dealing with large
enough images

https://bugzilla.gnome.org/show_bug.cgi?id=731195
oggstream: consider all opus packets as "keyframes"

This lets oggdemux determine they are not delta units, and removes
spurious per packet warnings about being unable to determine the
packet's keyframeness.
alsasink: fix occasional crash intersecting invalid values

When a pipeline using alsasink and push mode upstream fails
to preroll, the following state will be the case:
- A loop upstream will be PAUSED, pushing a first buffer
- alsasink will be READY, pending PAUSED, because async

On error, the pipeline will switch to NULL. alsasink is in
READY, so goes to NULL immediately. It zeroes its cached
caps. Meanwhile, the upstream loop can cause a caps query,
conccurent with the state change. This will use those cached
caps. If the zeroing happens between the NULL test and the
dereferencing, GStreamer will critical down in the GstValue
code.

Since it appears that such a gap between states (PAUSED
and pushing upstream, and NULL downstream) is expected, we
need to protect the read/write access to the cached caps.

This fixes the critical.

See https://bugzilla.gnome.org/show_bug.cgi?id=731121
decodebin: Do async-done on expose errors too
vorbisenc: add missing va_end in variadic function

Coverity 1139944
tcpserversrc: return FLOW_FLUSHING instead of an error when accept/select is canceled

Canceling the accept/select happens when the source is shut down. This is
not an error and the GST_FLOW_ERROR causes problems when only part of the
pipeline is shut down.

https://bugzilla.gnome.org/show_bug.cgi?id=731567
tcpclientsrc: return FLUSHING when select() is canceled

https://bugzilla.gnome.org/show_bug.cgi?id=731567
typefind: Bump iso mp4 typefinder to PRIMARY. Add mp4 extension hint.

Fixes a problem with at least one file being detected incorrectly as
DTS because there's DTS packets early enough in the file.
audiocdsrc: Don't consider trailing data tracks for MusicBrainz disc id calculation

MusicBrainz removes trailing data tracks from releases on the server
and also for the calculation of the MusicBrainz Disc ID.

https://bugzilla.gnome.org/show_bug.cgi?id=708991