Use long instead of int for MP3 sample counter.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=120331805

library/src/main/java/com/google/android/exoplayer/extractor/mp3/Mp3Extractor.java

@@ -67,7 +67,7 @@ public final class Mp3Extractor implements Extractor {
   private GaplessInfo gaplessInfo;
   private Seeker seeker;
   private long basisTimeUs;
-  private int samplesRead;
+  private long samplesRead;
   private int sampleBytesRemaining;
 
   /**