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
R=andrew@webrtc.org, kwiberg@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/54629004

Cr-Commit-Position: refs/heads/master@{#9405}

webrtc/modules/audio_coding/neteq/test/RTPencode.cc

@@ -1605,7 +1605,7 @@ int NetEQTest_encode(int coder,
                      int useVAD,
                      int bitrate,
                      int numChannels) {
-  short cdlen = 0;
+  int cdlen = 0;
   int16_t* tempdata;
   static int first_cng = 1;
   int16_t tempLen;