On Linux, these functions cannot fail. On Windows, mutexes cannot fail
and neither can real condition varaibles (but we use events instead to
support pre-Vista versions). In practice, the needed resources are
allocated as part of the mutex structure and per-thread data.

In any case, basically none of the call sites for those functions were
checking for errors. It seems best to abort in case of error than to
hit undefined behaviour. We probably do not want to clutter the tree
with untested never used error paths.

Those two functions can actually fail and leave the handle undefined.
vlc_join() and vlc_thread_join() would then crash (say, be undefined),
so errors should be taken care of explicitly.

Also remove conflict between browser back/forward and mouse wheel.

Signed-off-by: Felix Paul Kühne <fkuehne@videolan.org>

Doesn't work because variables callback can't be removed from their own callbacks.
Some work will be required here.

Those finer grained locks help the media_list_player.

Basically pause() might play(). This may need some revamping.

libvlc_Ended is the state we want to check.
When paused, if the media ended before, we need to allow that state.

Works here.

As WinCE doesn't support working directories, this function is
basically empty, and merely returns an error.

Should fix #2767.

Conflicts:

	src/control/media_player.c

var_Change(VLC_VAR_GETCHOICES). The memory was freed by a call to
var_Change(VLC_VAR_FREELIST). That's not a good idea as we were doing a lookup
just to free some memory.