Reland "Upconvert various types to int.", ilbc portion.

This reverts portions of commit cb180976dd0e9672cde4523d87b5f4857478b5e9, which
reverted commit 83ad33a8aed1fb00e422b6abd33c3e8942821c24.  Specifically, the
files in webrtc/modules/audio_coding/codecs/ilbc/ 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

Review URL: https://codereview.webrtc.org/1184643002

Cr-Commit-Position: refs/heads/master@{#9423}

webrtc/modules/audio_coding/codecs/ilbc/enhancer_interface.c

@@ -119,8 +119,8 @@ int WebRtcIlbcfix_EnhancerInterface( /* (o) Estimated lag in end of in[] */
     shifts = WEBRTC_SPL_MAX(0, shifts);
 
     /* compute cross correlation */
-    WebRtcSpl_CrossCorrelation(corr32, target, regressor,
-                               ENH_BLOCKL_HALF, 50, (int16_t)shifts, -1);
+    WebRtcSpl_CrossCorrelation(corr32, target, regressor, ENH_BLOCKL_HALF, 50,
+                               shifts, -1);
 
     /* Find 3 highest correlations that should be compared for the
        highest (corr*corr)/ener */
@@ -205,8 +205,8 @@ int WebRtcIlbcfix_EnhancerInterface( /* (o) Estimated lag in end of in[] */
       shifts=0;
 
     /* compute cross correlation */
-    WebRtcSpl_CrossCorrelation(corr32, target, regressor,
-                               plc_blockl, 3, (int16_t)shifts, 1);
+    WebRtcSpl_CrossCorrelation(corr32, target, regressor, plc_blockl, 3, shifts,
+                               1);
 
     /* find lag */
     lag=WebRtcSpl_MaxIndexW32(corr32, 3);