Fix the X11 build error

This makes qtmultimedia build again by moving down X11 includes.
See http://lists.qt-project.org/pipermail/development/2013-September/012986.html

Change-Id: If6cd5e80c27de7aaa8d2a65ded05500ed9d0e692
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Reviewed-by: Laszlo Papp <lpapp@kde.org>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Yoann Lopes <yoann.lopes@digia.com>