midori: bump to version 0.5.11

Also drop BR2_PACKAGE_MIDORI_HTTPS option since it's now handled in the
webkitgtk package to satisfy MiniBrowser.

This version can't work with the older webkitgtk24 engine so it switches
to the new version.

Also make gcr support conditional on x11 support for libgtk3, it doesn't
work otherwise.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>