Multisite: Add `$network_id` parameter to `get_user_count()`.

The `get_user_count()` function returns the number of active users on a network, which is stored in a `user_count` network option. Since `get_network_option()` supports retrieving options from other networks than the current one, `get_user_count()` can now make use of that feature.

Fixes #37866.

Built from https://develop.svn.wordpress.org/trunk@40371


git-svn-id: http://core.svn.wordpress.org/trunk@40278 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/ms-functions.php

@@ -96,11 +96,13 @@ function get_active_blog_for_user( $user_id ) {
  * The count is cached and updated twice daily. This is not a live count.
  *
  * @since MU 2.7
+ * @since 4.8.0 The $network_id parameter has been added.
  *
- * @return int
+ * @param int|null $network_id ID of the network. Default is the current network.
+ * @return int Number of active users on the network.
  */
-function get_user_count() {
-	return get_site_option( 'user_count' );
+function get_user_count( $network_id = null ) {
+	return get_network_option( $network_id, 'user_count' );
 }
 
 /**

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.8-alpha-40370';
+$wp_version = '4.8-alpha-40371';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.