X11_Util: Don't specify a background pixel

This causes flickering when resizing the window, which looks horrid
and we shouldn't do it.

Source/Core/DolphinWX/GLInterface/X11_Util.cpp

@@ -21,14 +21,12 @@ Window cX11Window::CreateXWindow(Window parent, XVisualInfo *vi)
 
 	// Setup window attributes
 	attr.colormap = colormap;
-	attr.background_pixel = BlackPixel(dpy, 0);
-	attr.border_pixel = 0;
 
 	// Create the window
 	win = XCreateWindow(dpy, parent,
 			    0, 0, 1, 1, 0,
 			    vi->depth, InputOutput, vi->visual,
-			    CWBorderPixel | CWBackPixel | CWColormap, &attr);
+			    CWColormap, &attr);
 	XSelectInput(dpy, parent, StructureNotifyMask);
 	XMapWindow(dpy, win);
 	XSync(dpy, True);