Coding Standards: Check if the `_deprecated_file()` function exists in `wp-db.php`.

This avoids a fatal error if the file is included directly outside of WordPress core, e.g. by HyperDB.

Additionally, replace `WPINC` with `wp-includes`, as the constant may not be defined yet in that context.

Follow-up to [53749], [53750].

See #56268, #55647.
Built from https://develop.svn.wordpress.org/trunk@53755


git-svn-id: http://core.svn.wordpress.org/trunk@53314 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.1-alpha-53754';
+$wp_version = '6.1-alpha-53755';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.

wp-includes/wp-db.php

@@ -8,7 +8,10 @@
  * @package WordPress
  */
 
-_deprecated_file( basename( __FILE__ ), '6.1.0', WPINC . '/class-wpdb.php' );
+if ( function_exists( '_deprecated_file' ) ) {
+	// Note: WPINC may not be defined yet, so 'wp-includes' is used here.
+	_deprecated_file( basename( __FILE__ ), '6.1.0', 'wp-includes/class-wpdb.php' );
+}
 
 /** wpdb class */
-require_once ABSPATH . WPINC . '/class-wpdb.php';
+require_once ABSPATH . 'wp-includes/class-wpdb.php';