Fixed application of memory limit in tests/lang/bug45392. Marked as XFAIL.

This old bugfix is not working as intended.
The memory limit in main's `PG(memory_limit)` differs from the one in zend_alloc.
In zend_alloc the `AG(mm_heap)->limit` is defined as `max(passed_value, ZEND_MM_CHUNK_SIZE)`.
The check made in an unclean shutdown will never be true unless the memory limit is lower than
ZEND_MM_CHUNK_SIZE, which happened to be the case in the test.
https://bugs.php.net/bug.php?id=45392
fcc0fdd

Author: pvandommelen

tests/lang/bug45392.phpt

@@ -2,6 +2,8 @@
 Bug #45392 (ob_start()/ob_end_clean() and memory_limit)
 --INI--
 display_errors=stderr
+--XFAIL--
+The issue has not yet been resolved.
 --SKIPIF--
 <?php
 if (getenv("USE_ZEND_ALLOC") === "0") {
@@ -10,7 +12,7 @@ if (getenv("USE_ZEND_ALLOC") === "0") {
 --FILE--
 <?php
 echo __LINE__ . "\n";
-ini_set('memory_limit', 100);
+ini_set('memory_limit', "2M");
 ob_start();
 $i = 0;
 while($i++ < 5000)  {