Update mp4 encapsulation spec to v0.5.3.

Based on http://vfrmaniac.fushizen.eu/contents/opus_in_isobmff.html
tests: fix linking for --enable-fixed-point on ARM
oggopus: Clarify leading zeros are ok for R128 tags.

Add a limit of no more than 6 characters for these tags' values.
oggopus: bump draft date and version for 05 publication.
oggopus: Improve wording.
oggopus: Fix opus_encode_ctl invocations.

The macros take arguments, they aren't just constants. Thanks to
mark4o for the report.
oggopus: Refer to 'TOC sequence' instead of byte.

This avoids confusion with the number of frames being defined
by more than the first byte with code 3 packets.

Patch from mark4o.
oggopus: Improve wording.
oggopus: use 'invalid' to match other occurances and RFC 6716.

Suggestion from mark4o.
oggopus: Refer to RFC 6716 on how to handle malformed packets.

The Opus RFC doesn't really say what to do beyond rejecting
a particular packet, but having the reference reinforces that
we're trying to leverage the same constraints in the specific
context of ogg encapsulation, and this isn't a new rule.
oggopus: Mention 'malformed' at the first instance of invalid TOC.

This is just a should, so we want to leave the RFC 6716 reference
to the second occurance, but using the same language ties them
together and to the later occurances.
oggopus: bump draft date and version for 06 publication.
float_cast: Fix MSVC ARM build

Signed-off-by: Tristan Matthews <tmatth@videolan.org>
RTP draft in last call
multistream: improve arg check

Avoid undefined behavior (signed arithmetic overflow) or
implementation-defined behavior (malloc(0)) on out-of-range arguments,
e.g. opus_multistream_encoder_create(48000, 2, 2147483647, 1, ...)
or opus_multistream_surround_encoder_create(48000, 3, 0, ...).

Signed-off-by: Jean-Marc Valin <jmvalin@jmvalin.ca>
Fix celt_pitch_xcorr_c signature.

This should not take an arch parameter, so it can properly be used
 as a fallback for accelerated versions which do not.
This patch instead provides a separate version which can call
 accelerated helpers for platforms that have taken that approach.
RTP draft: addressing comments from Martin Thompson