Matthew Waters authored Nov 13, 2012 and Tim-Philipp Müller committed Dec 09, 2017

- Make GstGLWindow subclassablerather than specified at compile time.
- Add GstGLWindowX11 for x11 windows and two subclasses, GstGLWindowX11GLX
  and GstGLWindwX11EGL for GLX and EGL repectively. (win32 and cocoa
  ports to come)
- Also cleanup GL library detection in configure.ac