vlc: fix configure failures with ENTERPRISE_DISTRO=1

VLC will by default search for libmad, liba52 and other libraries and may fail
to configure if they are not available. We add the relevant options to
EXTRA_OECONF to ensure that ENTERPRISE_DISTRO is respected.

Signed-off-by: Paul Barker <paul@paulbarker.me.uk>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>