desktop-shell: Set 1x1 buffers for solid-color backgrounds

When we are going to set a solid color for the background, use
a 1x1 buffer and set the viewport to the full size. This avoids
un-necessary allocation of buffer memory.

Signed-off-by: Harish Krupo <harish.krupo.kps@intel.com>

clients/desktop-shell.c

@@ -849,6 +849,12 @@ background_configure(void *data,
 		return;
 	}
 
+	if (!background->image) {
+		widget_set_viewport_destination(background->widget, width, height);
+		width = 1;
+		height = 1;
+	}
+
 	widget_schedule_resize(background->widget, width, height);
 }