Update a ton of audio code to use size_t more correctly and in general reduce
use of int16_t/uint16_t.

This is the upshot of a recommendation by henrik.lundin and kwiberg on an original small change ( https://webrtc-codereview.appspot.com/42569004/#ps1 ) to stop using int16_t just because values could fit in it, and is similar in nature to a previous "mass change to use size_t more" ( https://webrtc-codereview.appspot.com/23129004/ ) which also needed to be split up for review but to land all at once, since, like adding "const", such changes tend to cause a lot of transitive effects.

This was be reviewed and approved in pieces:
https://codereview.webrtc.org/1224093003
https://codereview.webrtc.org/1224123002
https://codereview.webrtc.org/1224163002
https://codereview.webrtc.org/1225133003
https://codereview.webrtc.org/1225173002
https://codereview.webrtc.org/1227163003
https://codereview.webrtc.org/1227203003
https://codereview.webrtc.org/1227213002
https://codereview.webrtc.org/1227893002
https://codereview.webrtc.org/1228793004
https://codereview.webrtc.org/1228803003
https://codereview.webrtc.org/1228823002
https://codereview.webrtc.org/1228823003
https://codereview.webrtc.org/1228843002
https://codereview.webrtc.org/1230693002
https://codereview.webrtc.org/1231713002

The change is being landed as TBR to all the folks who reviewed the above.

BUG=chromium:81439
TEST=none
R=andrew@webrtc.org, pbos@webrtc.org
TBR=aluebs, andrew, asapersson, henrika, hlundin, jan.skoglund, kwiberg, minyue, pbos, pthatcher

Review URL: https://codereview.webrtc.org/1230503003 .

Cr-Commit-Position: refs/heads/master@{#9768}
diff --git a/webrtc/modules/audio_coding/codecs/ilbc/encode.c b/webrtc/modules/audio_coding/codecs/ilbc/encode.c
index 114ce1f..812ec8d 100644
--- a/webrtc/modules/audio_coding/codecs/ilbc/encode.c
+++ b/webrtc/modules/audio_coding/codecs/ilbc/encode.c
@@ -48,11 +48,11 @@
     IlbcEncoder *iLBCenc_inst /* (i/o) the general encoder
                                      state */
                           ){
-  int n, meml_gotten, Nfor;
-  int16_t diff, start_pos;
-  int index;
-  int subcount, subframe;
-  int16_t start_count, end_count;
+  size_t n, meml_gotten, Nfor;
+  size_t diff, start_pos;
+  size_t index;
+  size_t subcount, subframe;
+  size_t start_count, end_count;
   int16_t *residual;
   int32_t en1, en2;
   int16_t scale, max;
@@ -86,7 +86,7 @@
 #ifdef SPLIT_10MS
 
   WebRtcSpl_MemSetW16 (  (int16_t *) iLBCbits_inst, 0,
-                         (int16_t) (sizeof(iLBC_bits) / sizeof(int16_t))  );
+                         sizeof(iLBC_bits) / sizeof(int16_t)  );
 
   start_pos = iLBCenc_inst->start_pos;
   diff = iLBCenc_inst->diff;
@@ -317,17 +317,17 @@
       if (iLBCenc_inst->section == 1)
       {
         start_count = 0;
-        end_count = WEBRTC_SPL_MIN (Nfor, 2);
+        end_count = WEBRTC_SPL_MIN (Nfor, (size_t)2);
       }
       if (iLBCenc_inst->section == 2)
       {
-        start_count = WEBRTC_SPL_MIN (Nfor, 2);
+        start_count = WEBRTC_SPL_MIN (Nfor, (size_t)2);
         end_count = Nfor;
       }
     }
 #else
     start_count = 0;
-    end_count = (int16_t)Nfor;
+    end_count = Nfor;
 #endif
 
     /* loop over subframes to encode */
@@ -341,7 +341,7 @@
                              &residual[(iLBCbits_inst->startIdx+1+subframe)*SUBL],
                              mem, MEM_LF_TBL, SUBL,
                              &weightdenum[(iLBCbits_inst->startIdx+1+subframe)*(LPC_FILTERORDER+1)],
-                             (int16_t)subcount);
+                             subcount);
 
       /* construct decoded vector */
 
@@ -386,7 +386,7 @@
        contained in the same vector as the residual)
     */
 
-    int Nback = iLBCbits_inst->startIdx - 1;
+    size_t Nback = iLBCbits_inst->startIdx - 1;
     WebRtcSpl_MemCpyReversedOrder(&reverseResidual[Nback*SUBL-1], residual, Nback*SUBL);
 
     /* setup memory */
@@ -434,7 +434,7 @@
     }
 #else
     start_count = 0;
-    end_count = (int16_t)Nback;
+    end_count = Nback;
 #endif
 
     /* loop over subframes to encode */
@@ -447,7 +447,7 @@
                              iLBCbits_inst->gain_index+subcount*CB_NSTAGES, &reverseResidual[subframe*SUBL],
                              mem, MEM_LF_TBL, SUBL,
                              &weightdenum[(iLBCbits_inst->startIdx-2-subframe)*(LPC_FILTERORDER+1)],
-                             (int16_t)subcount);
+                             subcount);
 
       /* construct decoded vector */