net-libs/webkit-gtk: sec bump to 2.22.4; require GL

net-libs/webkit-gtk: sec bump to 2.22.4; require GL

* Security bump to 2.22.4 for WSA-2018-0008
* Builds without GL (opengl or gles2) are currently broken, thus
  REQUIRED_USE it.
* Stop requiring gstreamer for introspection - seems to work fine
  without by now.
* GstreamerGL requires EGL, so REQUIRED_USE it by requiring EGL if
  USE="gstreamer opengl" (USE="gstreamer gles2" is already covered
  by gles2 itself also requiring egl).
* Raise gstreamer deps to ensure working MSE, as hopefully we can
  handle the stabilization of newer gst-plugins-opus for this
  security stabilization round.
* Add references to upstream bugs above REQUIRED_USE - we should
  monitor them on bumps to relax the requirements when/if the
  upstream bugs are fixed.

Closes: https://bugs.gentoo.org/671002
Signed-off-by: Mart Raudsepp <leio@gentoo.org>
Package-Manager: Portage-2.3.52, Repoman-2.3.11