PrefixAllGlobals: bugfix

Using the `DIRECTORY_SEPARATOR` constant will allow the sniff to be platform agnostic, so the unit tests will work on both Linux, Mac and Windows.

WPThemeReview/Sniffs/CoreFunctionality/PrefixAllGlobalsSniff.php

@@ -82,7 +82,7 @@ private function is_from_allowed_folder( $path ) {
 		}
 
 		foreach ( $this->allowed_folders as $folder ) {
-			if ( strrpos( $path, '/' . $folder . '/' ) !== false ) {
+			if ( strrpos( $path, DIRECTORY_SEPARATOR . $folder . DIRECTORY_SEPARATOR ) !== false ) {
 				return true;
 			}
 		}