Support the creation of >= 3.x OpenGL contexts

Use the EGL_KHR_create_context extension if available to create modern gl
contexts. We disable window decorations on core profiles because that
mandates a VAO to be used.

Change-Id: Id6044e64f6736244ae9d593af4d68c4000a31de6
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>