toytoolkit: Make the window resizing optimization optional

Whether or not a shm pool is used for resizing is now configurable at
build time (--disable-resize-optimization).

[pq: removed an unnecessary hunk from the patch]
diff --git a/clients/window.c b/clients/window.c
index 135ae5a..b2e1af7 100644
--- a/clients/window.c
+++ b/clients/window.c
@@ -1063,6 +1063,7 @@
 	if (leaf->cairo_surface)
 		cairo_surface_destroy(leaf->cairo_surface);
 
+#ifdef USE_RESIZE_POOL
 	if (resize_hint && !leaf->resize_pool) {
 		/* Create a big pool to allocate from, while continuously
 		 * resizing. Mmapping a new pool in the server
@@ -1073,6 +1074,7 @@
 		leaf->resize_pool = shm_pool_create(surface->display,
 						    6 * 1024 * 1024);
 	}
+#endif
 
 	rect.width = width;
 	rect.height = height;