macosx: dynamically create context and main sub menu for playlist table header selection, Simplifications in existing code

Regression from d70cda88.

The layout of struct addrinfo is variable (notably because of RFC5014),
so copying hints is brittle.

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

For consistency with 691e604c, libass doesn't need harfbuzz on Android. (It doesn't build anyway.)
Signed-off-by: Rafaël Carré <funman@videolan.org>

Pointed-out-by: Michał Trzebiatowski <hippie_1968@hotmail.com>

Qt ensures event IDs are never reused by providing a way to register
them dynamically. We have code that allocate event IDs statically and we
need to check/register those then to ensure proper offset for dynamic
ones. (we could just register them too, but this wouldn't allow
switch/case through values)

Close #7348
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

Plus one friendship was unused.

libavutil.h doesnt include common.h since lavu 51.39.

Unbreaks build on OSX.