qt5webkit: add WEBKIT_CONFIG+=use_glib on libsoup enabled builds

use_glib is set in gstreamer builds but not in libsoup only builds whereas there exist a dependency on glibc
rpi_webkitgtk_defconfig should enable webkitgtk-shell.
Enable HTML5 Video support in WebKitGTK+.
Add the patch that contains the necessary changes for zero-copy, efficient video rendering.
Bump the webkitgtk-shell commit tag.
Merge pull request #46 from zdobersek/webkitgtk

WebKitGTK+ update
libnice: add new package
v4l-utils: add new package
gst1-plugins-good: depend on v4l-utils

Only if the v4l2 plugins are needed.
qt5webkit: new option for WebRTC build
gstreamer1: move version to global gstreamer1.mk

GStreamer -core,-base,-good,-bad,-ugly,-libav share the same version
number for now.
gstreamer1: bump to 1.3.2
gst1-rpicamsrc: new package

This is a GStreamer video source element for the RPi webcam.
rpi-firmware: bump
linux: bump to 3.12.20