Database: Ensure MySQL port numbers are numeric in `wpdb`.

Ensure the database port number is recorded as an integer or `null` (the default port) when parsing the database host.

This is to prevent PHP/MySQLi throwing an exception caused by ports represented as numeric strings.

Props audrasjb, azouamauriac, chaion07, costdev, johnjamesjacoby, jrf, sergeybiryukov.
Fixes #54877.

Built from https://develop.svn.wordpress.org/trunk@53670


git-svn-id: http://core.svn.wordpress.org/trunk@53229 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.1-alpha-53669';
+$wp_version = '6.1-alpha-53670';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.

wp-includes/wp-db.php

@@ -2077,6 +2077,9 @@ class wpdb {
 			}
 		}
 
+		// MySQLi port cannot be a string; must be null or an integer.
+		$port = $port ? absint( $port ) : null;
+
 		return array( $host, $port, $socket, $is_ipv6 );
 	}