Updates a blog’s post count.

WordPress MS stores a blog’s post count as an option so as
to avoid extraneous COUNTs when a blog’s details are fetched
with get_site(). This function is called when posts are published
or unpublished to make sure the count stays current.

function update_posts_count( $deprecated = '' ) {
	global $wpdb;
	update_option( 'post_count', (int) $wpdb->get_var( "SELECT COUNT(ID) FROM {$wpdb->posts} WHERE post_status = 'publish' and post_type = 'post'" ) );
}