Skip boundry neutral characters in bidi itemization

Skip boundry neutral characters in bidi itemization

According to UAX #9, bidiItemize should act as if those characters
don't exist. If we don't, dir and status.eor here may become
QChar::DirBN, thus interfere the result of bidiItemize.

Task-number: QTBUG-19949
Reviewed-by: Lars Knoll
(cherry picked from commit a5c3064439a9f1483565e5d9dfbf0342cd9236f0)

Change-Id: I224cfdf5b38433a31d33b6d944d5770accf74546
Reviewed-on: http://codereview.qt.nokia.com/1631
Reviewed-by: Jiang Jiang <jiang.jiang@nokia.com>
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>