Plug two memory leaks

Plug two memory leaks introduced in the border drawing code.

sway/border.c

@@ -86,6 +86,8 @@ int get_font_text_height(const char *font) {
 	cairo_t *cr = cairo_create(surface);
 	int width, height;
 	get_text_size(cr, font, &width, &height, "Gg");
+	cairo_surface_destroy(surface);
+	cairo_destroy(cr);
 	return height;
 }
 

sway/container.c

@@ -64,6 +64,7 @@ static void free_swayc(swayc_t *cont) {
 	if (cont->bg_pid != 0) {
 		terminate_swaybg(cont->bg_pid);
 	}
+	free(cont->border);
 	free(cont);
 }