Update audio code to use size_t more correctly,

webrtc/common_audio/signal_processing/dot_product_with_scale.c

Index: webrtc/common_audio/signal_processing/dot_product_with_scale.c
diff --git a/webrtc/common_audio/signal_processing/dot_product_with_scale.c b/webrtc/common_audio/signal_processing/dot_product_with_scale.c
index c01ec57309ec32809e0e3305ebc40246e2a9766c..1302d62541266fdc45b07576de5ff5026d69032f 100644
--- a/webrtc/common_audio/signal_processing/dot_product_with_scale.c
+++ b/webrtc/common_audio/signal_processing/dot_product_with_scale.c
@@ -12,10 +12,10 @@
 
 int32_t WebRtcSpl_DotProductWithScale(const int16_t* vector1,
                                       const int16_t* vector2,
-                                      int length,
+                                      size_t length,
                                       int scaling) {
   int32_t sum = 0;
-  int i = 0;
+  size_t i = 0;
 
   /* Unroll the loop to improve performance. */
   for (i = 0; i + 3 < length; i += 4) {