Description:
------------
When assigning an object to a PDO statement via FETCH_INTO a memory leak occurs 
that can not be corrected through php code.  A subsequent FETCH_INTO with a 
different object only furthers the problem.  Changing the fetch mode, unsetting 
the statement, closing the cursor, and calling the garbage collection do not free 
the memory either. 

This bug exists in 5.2 and 5.3.

Test script:
---------------
<?php
if (! extension_loaded('pdo_sqlite')) {
	dl('pdo_sqlite.so');
}
$pdo = new PDO('sqlite::memory:');
echo "Start mem:".memory_get_peak_usage()."\n";

// Simple test
$stmt = $pdo->prepare("select 1 as attr");
for($i=0; $i<100000; $i++) {
	$stmt->setFetchMode(PDO::FETCH_INTO, new StdClass);
	echo "mem: ".memory_get_usage()."\n";

}
// End - Simple Test

// Alternate test with failed remedies
class test {
	public $attr;
	public function load($pdo) {
		$stmt = $pdo->prepare("select 1 as attr");
		//$stmt->setFetchMode(PDO::FETCH_INTO, $this); // This leaks quickly
		$stmt->setFetchMode(PDO::FETCH_INTO, new StdClass); // This still leaks
		$stmt->setFetchMode(PDO::FETCH_ASSOC); // You might think this would fix the leak - no effect
		$stmt->closeCursor(); // No effect
		unset($stmt); // No effect
	}
}

for($i=0; $i<100000; $i++) {
	$test = new test;
	$test->load($pdo);
	if (function_exists('gc_collect_cycles')) {
		echo "+gc+ ";
		gc_collect_cycles(); // No effect
	}
	unset($test);
	echo "mem: ".memory_get_peak_usage()."\n";
}



Expected result:
----------------
I would expect the peak memory usage to remain consisten on subsequent iterations.

Actual result:
--------------
The peak memory usage continues to rise until the php memory limit is hit.