QML examples: Avoid using release/debug output subdirectory

Qt Sensors examples that include additional QML modules fail
to run on Windows, because the application located under a
debug or release subdirectory does not see the module import
path.

This change fixes the issue by adjusting examples' DESTDIR
on Windows builds.

Task-number: QTBUG-33875
Change-Id: Iab8ebc1acd80cf4fe88a7a35b44c42f767da5ccf
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>