Merge branch '4.4' into 5.1

* 4.4:
  Bump ext-igbinary to 3.1.5 to fix compile error on php 8.
  [HttpClient] with "bindto" with NativeHttpClient

.travis.yml

@@ -183,7 +183,7 @@ before_install:
               tfold ext.redis tpecl redis-5.2.2 redis.so $INI "no"
           fi
 
-          tfold ext.igbinary tpecl igbinary-3.1.2 igbinary.so $INI
+          tfold ext.igbinary tpecl igbinary-3.1.5 igbinary.so $INI
       done
     - |
       # List all php extensions with versions

src/Symfony/Component/HttpClient/NativeHttpClient.php

@@ -214,7 +214,7 @@ final class NativeHttpClient implements HttpClientInterface, LoggerAwareInterfac
                 'disable_compression' => true,
             ], static function ($v) { return null !== $v; }),
             'socket' => [
-                'bindto' => $options['bindto'],
+                'bindto' => $options['bindto'] ?: '0:0',
                 'tcp_nodelay' => true,
             ],
         ];