Coding Standards: Correct $post parameter default values in link-template.php.

This commit corrects the default post ID parameter values used in several functions to bring them in line with their `int` doctypes (and the doctypes of their internal function calls).

More specifically,

* `get_page_link()`: `$post = false` changed to `$post = 0`
* `_get_page_link()`: `$post = false` changed to `$post = 0`
* `post_comments_feed_link()`: `$post_id = ''` changed to `$post_id = 0`

Follow-up to [1752], [4475], [6365], [9136], [9274], [21735], [24490], [32606], [37252].

Props justlevine.
See #63268.

git-svn-id: https://develop.svn.wordpress.org/trunk@60152 602fd350-edb4-49c9-b593-d223f7449a82

Author: SergeyBiryukov

src/wp-includes/link-template.php

@@ -388,7 +388,7 @@ function get_post_permalink( $post = 0, $leavename = false, $sample = false ) {
  *                               Default false.
  * @return string The page permalink.
  */
-function get_page_link( $post = false, $leavename = false, $sample = false ) {
+function get_page_link( $post = 0, $leavename = false, $sample = false ) {
 	$post = get_post( $post );
 
 	if ( 'page' === get_option( 'show_on_front' ) && (int) get_option( 'page_on_front' ) === $post->ID ) {
@@ -425,7 +425,7 @@ function get_page_link( $post = false, $leavename = false, $sample = false ) {
  *                               Default false.
  * @return string The page permalink.
  */
-function _get_page_link( $post = false, $leavename = false, $sample = false ) {
+function _get_page_link( $post = 0, $leavename = false, $sample = false ) {
 	global $wp_rewrite;
 
 	$post = get_post( $post );
@@ -834,7 +834,7 @@ function get_post_comments_feed_link( $post_id = 0, $feed = '' ) {
  * @param string $feed      Optional. Feed type. Possible values include 'rss2', 'atom'.
  *                          Default is the value of get_default_feed().
  */
-function post_comments_feed_link( $link_text = '', $post_id = '', $feed = '' ) {
+function post_comments_feed_link( $link_text = '', $post_id = 0, $feed = '' ) {
 	$url = get_post_comments_feed_link( $post_id, $feed );
 	if ( empty( $link_text ) ) {
 		$link_text = __( 'Comments Feed' );