make x11 dc could get cairo context, so the graphic module could use in x11. This use cairo xlib backend.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77853 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/graphicc.cpp

@@ -1744,6 +1744,12 @@ wxCairoContext::wxCairoContext( wxGraphicsRenderer* renderer, const wxWindowDC&
 #endif
 #endif
 
+#ifdef __WXX11__
+    cairo_t* cr = static_cast<cairo_t*>(dc.GetImpl()->GetCairoContext());
+    if ( cr )
+        Init(cairo_reference(cr));
+#endif
+
 #ifdef __WXMAC__
     CGContextRef cgcontext = (CGContextRef)dc.GetWindow()->MacGetCGContextRef();
     cairo_surface_t* surface = cairo_quartz_surface_create_for_cg_context(cgcontext, width, height);