Description of problem:
PDO ODBC truncates BLOB records at every 256th byte


Test script:
---------------
1. ODBC version:
$conn = odbc_connect("ORACLETEST", "user", "password");
$query = "SELECT pdf FROM PAYROLL WHERE USER_ID = 999 AND ROWNUM = 1 ORDER BY YEAR DESC, MONTH DESC";
if(!$conn) die("Connection failed");
if($result = odbc_exec($conn, $query))
{
    odbc_longreadlen($result, 131072);
    while(odbc_fetch_row($result)){
        print strlen(odbc_result($result,1));
    }
}

2. PDO ODBC version:
$pdo = new PDO("odbc:ORACLETEST", "user",  "password" );
$stmt = $pdo->prepare('SELECT pdf FROM PAYROLL WHERE USER_ID = 999 AND ROWNUM = 1 ORDER BY YEAR DESC, MONTH DESC');
$stmt->bindColumn(1, $data, PDO::PARAM_LOB);
$stmt->execute();
$stmt->fetch(PDO::FETCH_BOUND);
print strlen($data);

Upstream Fix:
https://github.com/php/php-src/pull/6716
https://bugs.php.net/bug.php?id=80783

Version-Release number of selected component (if applicable):
rh-php73-php-odbc-7.3.20-1.el7.x86_64
rh-php73-php-pdo-7.3.20-1.el7.x86_64



Expected result:
----------------
The actual data in the database is 25744 bytes long.


Actual result:
--------------
ODBC version returns with the length of 25744, and that's fine.

PDO ODBC version returns with the length of 25644 byte, which is 100 bytes smaller than expected.