Description:
------------
When executing exactly the same query, one non-prepared and one prepared, the prepared statement results in a VARCHAR filled with spaces the same length as the VARCHAR.

For example, if we create a table with a single VARCHAR(32), and insert an empty string using a straight db2_exec, the value is correct. However, if we insert an empty string using db2_prepare and db2_bind_param, the resulting string is actually 32 whitespace characters.

Test script:
---------------
<?php

$conn = db2_connect('<replace>', '<replace>', '<replace>', [
  'i5_naming' => DB2_I5_NAMING_OFF,
  'i5_lib' => '<replace>',
]);

db2_exec($conn, 'CREATE OR REPLACE TABLE FOO (BAR VARCHAR(32));');
db2_exec($conn, 'DELETE FROM FOO');

// Works fine
db2_exec($conn, "INSERT INTO FOO VALUES ('')");

// Preparing and executing results in 32 space characters
$stmt = db2_prepare($conn, 'INSERT INTO FOO VALUES (?)');

$value = '';
db2_bind_param($stmt, 1, "value", DB2_PARAM_IN);

var_dump(db2_execute($stmt));

// Dump the results
$r = db2_exec($conn, "SELECT * FROM FOO");
while ($row = db2_fetch_assoc($r)) {
  echo json_encode($row, JSON_PRETTY_PRINT) . "\n";
}


Expected result:
----------------
bool(true)
{
    "BAR": ""
}
{
    "BAR": ""
}

Actual result:
--------------
bool(true)
{
    "BAR": ""
}
{
    "BAR": "                                "
}