[gtk+/gtk-3-16] x11/gl: Do not use GLX_EXT_texture_from_pixmap if not available

[Emmanuele Bassi <ebassi src gnome org>]

commit c7dd439d4f8eaccf7712a389c53390a174c54224
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Thu Mar 26 17:26:29 2015 +0000

    x11/gl: Do not use GLX_EXT_texture_from_pixmap if not available
    
    If the GLX_EXT_texture_from_pixmap extension is not available when we
    did the extensions check, then there's no point in using the backend
    specific code paths that rely on it.

 gdk/x11/gdkglcontext-x11.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/gdk/x11/gdkglcontext-x11.c b/gdk/x11/gdkglcontext-x11.c
index d6126fc..fdf8ab2 100644
--- a/gdk/x11/gdkglcontext-x11.c
+++ b/gdk/x11/gdkglcontext-x11.c
@@ -432,6 +432,11 @@ gdk_x11_gl_context_texture_from_surface (GdkGLContext *paint_context,
   double sx, sy;
   float uscale, vscale;
   GdkTexturedQuad *quads;
+  GdkX11Display *display_x11;
+
+  display_x11 = GDK_X11_DISPLAY (gdk_gl_context_get_display (paint_context));
+  if (!display_x11->has_glx_texture_from_pixmap)
+    return FALSE;
 
   if (cairo_surface_get_type (surface) != CAIRO_SURFACE_TYPE_XLIB)
     return FALSE;