Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

The mutex needs to be unlocked while the thread sleeps. Otherwise, a
deadlock may occur in case of contention for the mutex.

Signaling an event ensures that at least one thread wakes up, but it
does not warrant that all of them do.

(No functional changes)

This avoids SIGPIPE firing when writing to a remote-closed connection-
oriented socket (it is useless for datagram sockets or on Windows
though). SIGPIPE is blocked ins VLC, but not necessarily in LibVLC.

The problem remains for write() on broken pipe and sockets.

Removes singleton, fixes initialization and deletion. Renames to
AddonsWindowController.

refs #14649

Removes sharedInstance from About window controller, and rework
as a NSWindowController subclass. This is the new owner of the xib
and thus instantiated outside the nib bundle.

Splits Help window in own xib and add own NSWindowController as
well.

refs #5556

Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>

Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>

Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>

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