Log Message:
Updated musicpd to 0.20.6.

ver 0.20.6 (2017/03/10)
* input
  - curl: fix headers after HTTP redirect to Shoutcast server
* decoder
  - ffmpeg: re-enable as fallback
  - mpcdec: fix crash (division by zero) after seeking
  - sidplay: make compatible with libsidplayfp < 1.8
* fix stream tags after automatic song change
* workaround for GCC 4.9.4 / libstdc++ bug (build failure)