SDK / exoplayer

If/when we add the ability to query version information,
such methods will go into FlacLibrary for consistency with
the other extensions. The difference for Flac is that
since the decoder JNI is used by the extractor too, it
needs splitting into a separate from from FlacDecoder.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=132904665