Fixed PCM endianness bug

[hendriks73]

Install a PCM encoder when the decoded output needs byte-order adjustment:

• 24-bit: decoder outputs S32-padded frames; encoder repacks to 24-bit
• multi-byte big-endian sources: FFmpeg's PCM decoder produces native-LE frames regardless of the on-disk byte order, so without an encoder the Java buffer would receive LE bytes while the AudioFormat reports BE.

This bug showed up, when decoding AIFF files.