Fix idn_to_utf8 stub signature

Signed-off-by: Côme Chilliet <come.chilliet@nextcloud.com>

build/stubs/intl.php

@@ -4622,7 +4622,7 @@ function idn_to_ascii($domain, $options = 0, $variant = INTL_IDNA_VARIANT_2003,
  * @param int $variant [optional] <p>
  * Either INTL_IDNA_VARIANT_2003 for IDNA 2003 or INTL_IDNA_VARIANT_UTS46 for UTS #46.
  * </p>
- * @param int &$idna_info [optional] <p>
+ * @param array &$idna_info [optional] <p>
  * This parameter can be used only if INTL_IDNA_VARIANT_UTS46 was used for variant.
  * In that case, it will be filled with an array with the keys 'result',
  * the possibly illegal result of the transformation, 'isTransitionalDifferent',
@@ -4634,7 +4634,7 @@ function idn_to_ascii($domain, $options = 0, $variant = INTL_IDNA_VARIANT_2003,
  * RFC 3490 4.2 states though "ToUnicode never fails. If any step fails, then the original input
  * sequence is returned immediately in that step."
  */
-function idn_to_utf8($domain, $options = 0, $variant = INTL_IDNA_VARIANT_2003, array &$idna_info) { }
+function idn_to_utf8($domain, $options = 0, $variant = INTL_IDNA_VARIANT_2003, array &$idna_info = null) { }
 
 /**
  * (PHP 5 &gt;=5.5.0 PECL intl &gt;= 3.0.0a1)<br/>