Fix hypothetical issue with encrypted CEA608

This will never happen in practice, since CEA608 shouldn't be encrypted (and we
can't handle it if it is), but in theory appendSampleEncryptionData can be called,
then skipFully can throw when applying the CEA608 transformation, then when
retrying appendSampleEncryptionData will be called again for the same sample.
appendSampleEncryptionData consumes from trackFragment.sampleEncryptionData, and
so the second time around data is being consumed one sample ahead.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=189931631

library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/FragmentedMp4Extractor.java

@@ -1140,16 +1140,16 @@ public final class FragmentedMp4Extractor implements Extractor {
       }
       sampleSize = currentTrackBundle.fragment
           .sampleSizeTable[currentTrackBundle.currentSampleIndex];
+      if (currentTrackBundle.track.sampleTransformation == Track.TRANSFORMATION_CEA608_CDAT) {
+        sampleSize -= Atom.HEADER_SIZE;
+        input.skipFully(Atom.HEADER_SIZE);
+      }
       if (currentTrackBundle.fragment.definesEncryptionData) {
         sampleBytesWritten = appendSampleEncryptionData(currentTrackBundle);
         sampleSize += sampleBytesWritten;
       } else {
         sampleBytesWritten = 0;
       }
-      if (currentTrackBundle.track.sampleTransformation == Track.TRANSFORMATION_CEA608_CDAT) {
-        sampleSize -= Atom.HEADER_SIZE;
-        input.skipFully(Atom.HEADER_SIZE);
-      }
       parserState = STATE_READING_SAMPLE_CONTINUE;
       sampleCurrentNalBytesRemaining = 0;
     }