Merge branch 'refs/heads/t/wma'

Merge branch 'refs/heads/t/wma'

A couple of patches which simplify the wma decoder and improve the
robustness of the bitstream API.

Cooking for a month.

* refs/heads/t/wma:
  wma: Remove _XOPEN_SOURCE define from wmadec_filter.c.
  wma: make ->ms_stereo local to wma_decode_block().
  wma: Simplify init_coef_vlc().
  wma: Rename input/output buffer variables.
  wma: Drop unused argument from wma_decode_superframe().
  wma: Remove pointless/incorrect sanity checks.
  wma: Combine wmadec_cleanup() and wmadec_close().
  wma: Simplify get_vlc().
  wma: Remove pointless VLC_TYPE define.
  wma: Make bitstream API more robust.