C++: Normalize line ending for preprocessing

There is logic in the preprocessor that assumes a normalized line
ending. Other patches have already fixed the issue in other parts.

Change-Id: Iac262da361b6528cc9466a6c87e83da95af9ea04
Reviewed-on: http://codereview.qt.nokia.com/4252


Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Christian Kamm <christian.d.kamm@nokia.com>