Description:
------------
Hello.
Function ftp_size() woks strange for files which size is mjre then 2^16 bytes. 
When checking size after uploading it returns -1. But if close and open connection it returns the correct result (after sprintf('%u', $size));
So, this function could not determine size of big file until reconnect.

Reproduce code:
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<?php

$start_time = microtime(TRUE);
$ftp_ip = 'ftp_ip';
$local_file = 'local_file.fil';
$remote_file = 'file_1.fil';

$conn = ftp_connect($ftp_ip, 21);
ftp_login($conn, 'anonymous','anonymous@mail.ml');
ftp_pasv($conn, TRUE);

echo "\n Time spent: ".(microtime(TRUE) - $start_time)."s... Trying to upload ".sprintf('%u', filesize($local_file))." bytes.\n";
echo "\n Time spent: ".(microtime(TRUE) - $start_time)."s... 1st attempt: ftp_put_returned: ".(ftp_put($conn, $remote_file, $local_file, FTP_BINARY)?'TRUE':'FALSE')."\n";
echo "\n Time spent: ".(microtime(TRUE) - $start_time)."s... Size of uploaded file before reconnect: ".sprintf('%u', ftp_size($conn, $remote_file))." (".ftp_size($conn, $remote_file).") bytes\n";
echo "\nReconnect...\n";

ftp_close($conn);
$conn = ftp_connect($ftp_ip, 21);
ftp_login($conn, 'anonymous','anonymous@mail.ml');
ftp_pasv($conn, TRUE);

echo "\n Time spent: ".(microtime(TRUE) - $start_time)."s... Size of uploaded file after reconnect: ".sprintf('%u', ftp_size($conn, $remote_file))." (".ftp_size($conn, $remote_file).") bytes\n";
ftp_close($conn);

?>

Actual result:
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 Time spent: 0.01035213470459s... Trying to upload 3532439032 bytes.
 Time spent: 0.010672092437744s... 1st attempt: ftp_put_returned: FALSE
 Time spent: 661.11731815338s... Size of uploaded file before reconnect: 4294967295 (-1) bytes
Reconnect...
 Time spent: 661.12095808983s... Size of uploaded file after reconnect: 3532439032 (-762528264) bytes