Windows: Fix inclusion of <windows.h>

Windows: Fix inclusion of <windows.h>

- Always use <qt_windows.h> as the last file to be included.
- Remove it from some headers, use Qt::HANDLE instead of HANDLE.
- Clean up #ifdef, use Q_OS_WIN for Windows/Windows CE.
- Add NOMINMAX to qt_windows.h to avoid problems with the
  min/max macros.
- Remove <windows.h> from qplatformdefs.h (VS2005)

Change-Id: Ic44e2cb3eafce38e1ad645c3bf85745439398e50
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@nokia.com>