Remove unused local variable in AudioTrack.java.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=144443010

library/src/main/java/com/google/android/exoplayer2/audio/AudioTrack.java

@@ -641,7 +641,6 @@ public final class AudioTrack {
       }
       }
     }
     }
 
 
-    int result = 0;
     if (isNewSourceBuffer) {
     if (isNewSourceBuffer) {
       // We're seeing this buffer for the first time.
       // We're seeing this buffer for the first time.