This is a partial revert of [6fdf44fd]

Should close #4011

MessageBoxA() isn't supported on WinCE

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

Preparation for adding assembly hue/saturation processing functions

Two new function pointers in p_sys to clipping and non-clipping U and V channel processing cycle
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

If we are going to create a window just to print an error message, I
think a native message box is nicer.

--miface-addr mostly did not work as --miface was supposed to be used
instead.

 * Do not force definitions on Windows so that compilation works with
   all variants of MingW (this may break IPv6 SSM with old compilers).
 * Do not fall back to legacy IPv4-specific ioctls if RFC3678 is
   supported. This avoids compiling dead code and works around issues
   with Linux kernel headers (especially Android).
 * Do not attempt to set multicast interface with legacy IPv4 ioctls.
   It is not very clear whether this is the address or the index.
   Also, "--miface-addr" was very confusing as it was mostly ignored in
   favor of "--miface".

macosx: removed 'erase logo' from the video effects panel and moved 'add logo' to the overlay stuff (now called Miscellaneous)

Fix #4479
See https://bugs.kde.org/show_bug.cgi?id=279973

Sometimes fonts are muxed with the wrong MIME type, but we should
still be able to use them. Especially OpenType font collections are
affected by this. Match attachments by extensions .ttf, .otf and .ttc
in addition to MIME type to fix these issues.
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

Add a message callback function to get libass messages into VLC's
logging system.
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

 - command line help text
 - text domain binding

No need to load the config file twice anymore.

This must be a bug in the SDK, so better ignore the header.

don't start variables with _, they have local scope anyway

This avoids allocating memory and formatting debug messages when none
of the subscribers care about them.