Call _update_fds() directly.  This is possible because it's only
called from within the I/O thread.

Fix deadlock.

Add -DNDEBUG to AM_CPPFLAGS.

Conflicts:
	NEWS
	configure.ac

Let the codec start with fresh buffers.  This should fix the remaining
seeking issues.

Use AVStream.time_base to convert the decoder_seek_where() value, and
pass the current stream number to av_seek_frame().

Use flag AV_TIME_BASE.

Code simplification.

Reduce heap usage by reducing the number of malloc() / free() calls.

The global data structures are now lock-free, because they are
accessed only from the I/O thread.  By using per-request locks, we
have finer grained locking, preparing for locks shared with the
client.

This adds some overheads for indirect calls to the I/O thread, but
reduces the amount of global locks.  Next step will be switching to
per-request locks.

Move the assignment to _request_done(), right before the GCond is
signalled.  This might fix spurious wakeups.

This is a trivial function.  Merge some duplicate code, e.g. the
g_cond_broadcast() call.

Update the struct attributes, important for facades like the "rewind"
plugin.  To replace buffer().

This is not necessary since all relevant input plugins have been moved
to the I/O thread, and there is no remaining useful buffer()
implementation.  This also fixes a busy loop when playing radio.

Needed for the I/O thread.

Use it in handle_lsinfo(), and eliminate some duplicate code.

Add nonnull attributes and fix all callers.

This is specific to gcc, not to mpd.