fix no perm for pcntl_unshare(42)

Author: mvorisek

ext/pcntl/tests/pcntl_unshare_04.phpt

@@ -6,6 +6,7 @@ posix
 --SKIPIF--
 <?php
 if (!function_exists("pcntl_unshare")) die("skip pcntl_unshare is not available");
+if (file_exists('/etc/alpine-release')) { die('skip no privilege on Alpine OS in Github CI'); }
 ?>
 --FILE--
 <?php