Fix ChromeOS build (C99 break)

BUG=5016
TBR=henrik.lundin@webrtc.org

Review URL: https://codereview.webrtc.org/1354163002

Cr-Commit-Position: refs/heads/master@{#9992}

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

@@ -22,8 +22,9 @@ void WebRtcIlbcfix_NearestNeighbor(size_t* index,
                                    const size_t* array,
                                    size_t value,
                                    size_t arlength) {
+  size_t i;
   size_t min_diff = (size_t)-1;
-  for (size_t i = 0; i < arlength; i++) {
+  for (i = 0; i < arlength; i++) {
     const size_t diff =
         (array[i] < value) ? (value - array[i]) : (array[i] - value);
     if (diff < min_diff) {