General: Memoize the return value in `wp_get_wp_version()`.

This aims to optimize performance by saving the return value to a static variable, so that the `version.php` file is not unnecessarily required on each function call.

Follow-up to [58813].

Props Cybr, debarghyabanerjee, mukesh27.
Fixes #61782. See #61627.
Built from https://develop.svn.wordpress.org/trunk@58827


git-svn-id: http://core.svn.wordpress.org/trunk@58223 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/functions.php

@@ -8819,7 +8819,11 @@ function clean_dirsize_cache( $path ) {
  * @return string The current WordPress version.
  */
 function wp_get_wp_version() {
+	static $wp_version;
+
+	if ( ! isset( $wp_version ) ) {
 		require ABSPATH . WPINC . '/version.php';
+	}
 
 	return $wp_version;
 }

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.7-alpha-58826';
+$wp_version = '6.7-alpha-58827';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.