Description:
------------
stream_set_timeout() doesn't seem to work on a blocking ssh2_exec() stream.

Reproduce code:
---------------
$con=ssh2_connect('ssss', 22);
ssh2_auth_password($con, "xxx", "yyy");
$exec = ssh2_exec($con, '/path/to/application');
$a = microtime(TRUE);
stream_set_blocking($exec, TRUE);
stream_set_timeout($exec, 1);
$buffer = trim(fgets($exec));
if (empty($buffer)) {
	$buffer = "EMPTY";
}
echo "Result: $buffer in " . round((microtime(TRUE) - $a)*1000, 1) . "ms";


Expected result:
----------------
EMPTY after ~ sec

Actual result:
--------------
Example code will stall >1 sec if the executable executes a sleep(10);