Description:
------------
If a native prepared statement is reused, it will leak memory on each reuse.
If the statement is prepared each time, there is no memory leak.

All versions of PHP 7.2 works, and all versions of PHP 7.3 leaks memory.

Versions:
Percona MySQL 5.7 & 8.0
PHP 7.3.x
Mysqlnd: mysqlnd 5.0.12-dev

The call to closeCursor() doesn't change anything.

Test script:
---------------
$pdo = new \PDO('mysql:host=<host>;dbname=<dbname>', 'user', 'password');

$pdo->setAttribute(\PDO::ATTR_EMULATE_PREPARES, false);

$stmt = $pdo->prepare('SELECT field FROM table LIMIT 100');

for($i=0;$i<250000;$i++)
{
	$stmt->execute();
	
	$stmt->fetchAll();
	
	//$stmt->closeCursor();
	
	if($i%1000 === 0) print memory_get_usage()."\r\n";
}

Expected result:
----------------
PHP 7.2.22:
446824
446856
446856
446856
446856
446856
446856
446856
446856
446856
446856
446856
446856
446856
446856

Actual result:
--------------
PHP 7.3.9:
479176
970728
1445864
1937384
2428904
2920424
3411944
3903464
4378600
4870120
5361640
5853160
6344680
6836200
7327720