[gtk] (25 commits) ...Merge branch 'wip/otte/gl-hdr' into 'master'

[Matthias Clasen <matthiasc src gnome org>]

Summary of changes:

  d939f37... win32: Comment out unused function (*)
  6ec6bca... win32: Remove unused variables (*)
  75370a2... pathbar: Use correct marshaler (*)
  38461ee... gdk: Make GDK_DEBUG GL backend selection global (*)
  9012a03... widget-factory: Name the images pages (*)
  04da2ff... surface: Use g_clear_thing() (*)
  ae8de71... build: Add a HAVE_EGL define to config.h (*)
  bfb158d... egl: Move initialization code and port Wayland (*)
  70607f5... x11: Port to shared EGL code (*)
  032eb15... glcontext: The content cannot be the current context (*)
  c8204a9... surface: Add a private struct (*)
  aba37c4... display: Get carried away by extension checker (*)
  d128ffc... egl: Move EGLSurface handling to GdkSurface (*)
  f8b9b30... egl: Move extension checks to GdkDisplay (*)
  482845b... wayland: Remove initial GL API bind (*)
  111c276... cairo-gl: Don't leak framebuffers (*)
  64f10ef... gdk: Remove unused gdk_gl_texture_quads() function (*)
  03cc603... glcontext: Remove unused functionality (*)
  2ff1ea5... egl: Unify contexts (*)
  3ca84c4... glcontext: Handle failure of eglBindAPI() (*)
  bc7c0d0... egl: Support EGL_KHR_no_config_context (*)
  7ede468... gdk: Add a request_hdr argument to begin_frame() (*)
  5eb42dd... gdk: Add GDK_DEBUG=hdr (*)
  cdc8523... egl: Implement HDR support (*)
  0969d9d... Merge branch 'wip/otte/gl-hdr' into 'master'

(*) This commit already existed in another branch; no separate mail sent