Upgrades: Update $_old_files for WordPress 5.1.

`wp-includes/random_compat/random_bytes_openssl.php` was removed in [43130], this commit updates `$_old_files` to match.

Merges [44760] to the 5.1 branch.

Fixes #46284.



git-svn-id: https://develop.svn.wordpress.org/branches/5.1@44761 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/includes/update-core.php

@@ -783,6 +783,7 @@
 	// 5.0
 	'wp-includes/js/codemirror/jshint.js',
 	// 5.1
+	'wp-includes/random_compat/random_bytes_openssl.php',
 	'wp-includes/js/tinymce/wp-tinymce.js.gz',
 );