Fix initital evaluation of ignore-whitespace and patience flags in
git diff.

Task-number: QTCREATORBUG-5176
Change-Id: Ibe3652ca6426fbc6e7187140b1d101afbec6c5ae
Reviewed-on: http://codereview.qt.nokia.com/2509


Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@nokia.com>