Formatting: Rely on _wp_can_use_pcre_u() to detect UTF-8 PCRE support.

The `sanitize_file_name()` function attempts to detect UTF-8 PCRE support, but WordPress already provides a more robust method. It then caches its check in a static var, which WordPress already does in the canonical function `_wp_can_use_pcre_u()`.

This patch refactors `sanitize_file_name()` to call `_wp_can_use_pcre_u()` directly instead of (mostly) recreating and recaching Core’s detection algorithm.

Developed in #9678
Discussed in https://core.trac.wordpress.org/ticket/63863

Follow-up to [60694].

Props dmsnell.
See #63863.


git-svn-id: https://develop.svn.wordpress.org/trunk@60695 602fd350-edb4-49c9-b593-d223f7449a82

Author: dmsnell

src/wp-includes/formatting.php

@@ -2195,20 +2195,13 @@ function sanitize_file_name( $filename ) {
 
 	$special_chars = array( '?', '[', ']', '/', '\\', '=', '<', '>', ':', ';', ',', "'", '"', '&', '$', '#', '*', '(', ')', '|', '~', '`', '!', '{', '}', '%', '+', '’', '«', '»', '”', '“', chr( 0 ) );
 
-	// Check for support for utf8 in the installed PCRE library once and store the result in a static.
-	static $utf8_pcre = null;
-	if ( ! isset( $utf8_pcre ) ) {
-		// phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
-		$utf8_pcre = @preg_match( '/^./u', 'a' );
-	}
-
 	if ( ! wp_is_valid_utf8( $filename ) ) {
 		$_ext     = pathinfo( $filename, PATHINFO_EXTENSION );
 		$_name    = pathinfo( $filename, PATHINFO_FILENAME );
 		$filename = sanitize_title_with_dashes( $_name ) . '.' . $_ext;
 	}
 
-	if ( $utf8_pcre ) {
+	if ( _wp_can_use_pcre_u() ) {
 		/**
 		 * Replace all whitespace characters with a basic space (U+0020).
 		 *