Code Modernization: Remove unnecessary reference sign from `PO::export_entry()` definition.

This fixes a PHP 8 "argument must be passed by reference, value given" error when using `array_map()` in `PO::export_entries()`.

Object variables in PHP 5+ contain a reference to the object, and it's the reference that's passed around.

Props jrf.
See #50913.
Built from https://develop.svn.wordpress.org/trunk@49186


git-svn-id: http://core.svn.wordpress.org/trunk@48948 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/pomo/po.php

@@ -212,11 +212,11 @@ if ( ! class_exists( 'PO', false ) ) :
 		/**
 		 * Builds a string from the entry for inclusion in PO file
 		 *
-		 * @param Translation_Entry $entry the entry to convert to po string (passed by reference).
+		 * @param Translation_Entry $entry the entry to convert to po string.
 		 * @return string|false PO-style formatted string for the entry or
 		 *  false if the entry is empty
 		 */
-		public static function export_entry( &$entry ) {
+		public static function export_entry( $entry ) {
 			if ( null === $entry->singular || '' === $entry->singular ) {
 				return false;
 			}

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.6-alpha-49185';
+$wp_version = '5.6-alpha-49186';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.