Allow x-default hreflang also if multiple alternate links are available

[markusreis]

Hey Dennis,

another filter request:

In your output code, the x-default only gets printed if there is only one alternate-link available. However, when for example offering two options alternate="de_DE" and alternate="en_US" you still might want to offer an x-default for all users from other countries. With this change you can then simply set the following to append the x-default link to the output for the desired default blog:

add_filter('mlsl_output_x_default_locale', function ($in) {
    return 'de_DE';
});

Will also solve this guys problem https://wordpress.org/support/topic/x-default-hreflang/ ;)

Cheers!