Two small fixes for HLS.

1. Clear prefixFlags when a NAL unit is found.
2. continueBuffering should return true if loading is finished.

library/src/main/java/com/google/android/exoplayer/hls/HlsSampleSource.java

@@ -164,7 +164,7 @@ public class HlsSampleSource implements SampleSource, Loader.Callback {
     if (!extractors.isEmpty()) {
       discardSamplesForDisabledTracks(extractors.getFirst(), downstreamPositionUs);
     }
-    return continueBufferingInternal();
+    return loadingFinished || continueBufferingInternal();
   }
 
   private boolean continueBufferingInternal() throws IOException {

library/src/main/java/com/google/android/exoplayer/mp4/Mp4Util.java

@@ -171,6 +171,9 @@ public final class Mp4Util {
         // loop advance the index by three.
       } else if (data[i - 2] == 0 && data[i - 1] == 0 && data[i] == 1
           && matchesType(data, i + 1, type)) {
+        if (prefixFlags != null) {
+          clearPrefixFlags(prefixFlags);
+        }
         return i - 2;
       } else {
         // There isn't a NAL prefix here, but there might be at the next position. We should