LIKE escape sanity:

* Deprecate `like_escape()`
* Add a method to `$wpdb`, `->esc_like()`, and add unit tests

`$wpdb::esc_like()` is not used yet. As such, many unit tests will throw `Unexpected deprecated notice for like_escape`. Subsequent commits will alleviate this.

Props miqrogroove.
See #10041.


git-svn-id: https://develop.svn.wordpress.org/trunk@28711 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/formatting.php

@@ -3099,18 +3099,6 @@ function tag_escape($tag_name) {
 	return apply_filters( 'tag_escape', $safe_tag, $tag_name );
 }
 
-/**
- * Escapes text for SQL LIKE special characters % and _.
- *
- * @since 2.5.0
- *
- * @param string $text The text to be escaped.
- * @return string text, safe for inclusion in LIKE query.
- */
-function like_escape($text) {
-	return str_replace(array("%", "_"), array("\\%", "\\_"), $text);
-}
-
 /**
  * Convert full URL paths to absolute paths.
  *