Description:
------------
oci_close() fails if the connection resource is a global accessed via the "global" keyword, but works if accessed using the $GLOBALS array.

Reproduce code:
---------------
$conn = oci_connect(DB_USER, DB_PASS, DB_NAME);
var_dump($conn);

global_keyword();
global_array();

function global_keyword()
{
    global $conn;
    var_dump($conn);
    oci_close($conn);  // this seems to do nothing
    var_dump($conn);
}

function global_array()
{
    var_dump($GLOBALS["conn"]);
    oci_close($GLOBALS["conn"]);  // this works
    var_dump($GLOBALS["conn"]);
}


Expected result:
----------------
resource(8) of type (oci8 connection)
resource(8) of type (oci8 connection)
NULL
NULL
PHP Warning: oci_close() expects parameter 1 to be resource, null given
NULL


Actual result:
--------------
resource(8) of type (oci8 connection)
resource(8) of type (oci8 connection)
resource(8) of type (oci8 connection)
resource(8) of type (oci8 connection)
NULL