Add test with wrong result

Author: ndossche

ext/zlib/tests/gzseek_seek_oob.phpt

@@ -0,0 +1,20 @@
+--TEST--
+Test function gzseek() by seeking out of bounds
+--EXTENSIONS--
+zlib
+--FILE--
+<?php
+$f = __DIR__."/004.txt.gz";
+$h = gzopen($f, 'r');
+
+var_dump(gzseek($h, -100, SEEK_CUR));
+var_dump(gzseek($h, 0, SEEK_CUR));
+var_dump(gztell($h));
+
+gzclose($h);
+?>
+--EXPECTF--
+int(-1)
+php: %s: _php_stream_seek: Assertion `stream->position >= 0' failed.
+
+Termsig=6