Reland "Upconvert various types to int.", misc. codecs portion.

Reland "Upconvert various types to int.", misc. codecs portion.

This reverts portions of commit cb180976dd0e9672cde4523d87b5f4857478b5e9, which
reverted commit 83ad33a8aed1fb00e422b6abd33c3e8942821c24.  Specifically, the
files in webrtc/modules/audio_coding/codecs/ that are not in ilbc/ or isac/, as
well as webrtc/modules/audio_coding/main/test/opus_test.cc, are relanded.

The original commit message is below:

Upconvert various types to int.

Per comments from HL/kwiberg on https://webrtc-codereview.appspot.com/42569004 , when there is existing usage of mixed types (int16_t, int, etc.), we'd prefer to standardize on larger types like int and phase out use of int16_t.

Specifically, "Using int16 just because we're sure all reasonable values will fit in 16 bits isn't usually meaningful in C."

This converts some existing uses of int16_t (and, in a few cases, other types such as uint16_t) to int (or, in a few places, int32_t).  Other locations will be converted to size_t in a separate change.

BUG=none
TBR=kwiberg

Committed: https://crrev.com/bba780707848ad36066739c60d7b28cd752fb92f
Cr-Commit-Position: refs/heads/master@{#9424}

[Peter Kasting, 2015-06-12 00:58:14]

pkasting@chromium.org changed reviewers:
+ kwiberg@webrtc.org
- kwiberg@chromium.org

[Peter Kasting, 2015-06-12 02:03:05]

Committed patchset #1 (id:1) manually as
bba780707848ad36066739c60d7b28cd752fb92f (presubmit successful).

[commit-bot: I haz the power, 2015-06-12 02:03:07]

Patchset 1 (id:??) landed as
https://crrev.com/bba780707848ad36066739c60d7b28cd752fb92f
Cr-Commit-Position: refs/heads/master@{#9424}

[kwiberg-webrtc, 2015-06-16 19:47:24]

lgtm