Skip drawing for uninitialized surfaces.

We return early from drawing functions if the surface to draw to is not
initialized properly. There is no immediate need to do so, at least no
crashes have been observed, but it mirrors the previous behavior a bit
more closely. Furthermore, i3 should not crash due to not being able to
make some rendering call, so this provides some stability.

relates to #1278

src/x.c

@@ -518,7 +518,7 @@ void x_draw_decoration(Con *con) {
     if (p->border_style != BS_NORMAL)
         goto copy_pixmaps;
 
-    /* If the parent hasn't been set up yet, skip the decoratin rendering
+    /* If the parent hasn't been set up yet, skip the decoration rendering
      * for now. */
     if (parent->frame_buffer.id == XCB_NONE)
         goto copy_pixmaps;