Fix file clash in zlib test

Author: nikic

ext/zlib/tests/gzseek_variation4.phpt

@@ -8,7 +8,7 @@ if (!extension_loaded("zlib")) {
 ?>
 --FILE--
 <?php
-$f = "gzseek_variation5.gz";
+$f = "gzseek_variation4.gz";
 $h = gzopen($f, 'w');
 $str1 = "This is the first line.";
 $str2 = "This is the second line.";