[client] x11: change to a more visible "dot" cursor

This change alters the small square dot cursor to a more visible 16x16
cursor for X11. A new option `spice:largeDotCursor` can be set to use an
alternative 32x32 cursor for the vision impaired.

client/src/main.c

@@ -1337,6 +1337,7 @@ static int lg_run(void)
     .resizable           = g_params.allowResize,
     .borderless          = g_params.borderless,
     .maximize            = g_params.maximize,
+    .largeCursorDot      = g_params.largeCursorDot,
     .opengl              = needsOpenGL,
     .jitRender           = g_params.jitRender
   };