Merge common code.

Eliminate duplicate code.

Checkbashisms (part of the Debian devscripts) pionted this out.

Be sure to stop the operation at some point when the server isn't
responding.

Check if the stream is suspended; wake up the main loop when it
becomes suspended.

Not a bool.

Unlock the mainloop in all code paths.

This warning should only be logged when we really received something.
When the client disconnects, G_IO_IN is triggered, and the read
returns G_IO_STATUS_EOF.

Move the variable "vbr_update_acc" into the #ifdef block.

In the "vorbis" plugin, this is a copy of the old flush() method,
while flush() gets a lot of code remove, it just sets the "flush" flag
and nothing else.  It doesn't start a new stream now, which should fix
a few problems in some players.

Enable gcc optimizations.

The method may take longer, and we shouldn't be holding the lock.

It used to ignore the decoder_data() return value.

libwavpack provides int32_t samples, and wants uin32_t for sample
counts.

.. and remove one indent level.

Use a shortcut in playlist_seek_song(), don't call
playlist_play_order() because that would reset the "paused" state.

av_open_input_stream() has been deprecated.

AVMetadata has been deprecated.

For accessing the child of a directory, one needs X_OK on the
directory.

This patch seems a bit ugly, maybe it would be a bit cleaner with gotos.

Was always displayed as "no", even if one was found.