RTP: Add log throttle for "no data".

Change-Id: I14d9886a40fa780514cbc6c5bac6fb2a670f55f4
diff --git a/voip/jni/rtp/AudioGroup.cpp b/voip/jni/rtp/AudioGroup.cpp
index 726e98b..7cf06137 100644
--- a/voip/jni/rtp/AudioGroup.cpp
+++ b/voip/jni/rtp/AudioGroup.cpp
@@ -104,6 +104,7 @@
     int mSampleRate;
     int mSampleCount;
     int mInterval;
+    int mLogThrottle;
 
     int16_t *mBuffer;
     int mBufferMask;
@@ -278,7 +279,10 @@
         chain = chain->mNext;
     }
     if (!mixed) {
-        LOGD("stream[%d] no data", mSocket);
+        if ((mTick ^ mLogThrottle) >> 10) {
+            mLogThrottle = mTick;
+            LOGD("stream[%d] no data", mSocket);
+        }
         return;
     }