Mark unused variables to prevent compiler warnings if using older geos.

Author: timlinux

src/app/qgsmaptooloffsetcurve.cpp

@@ -374,6 +374,9 @@ void QgsMapToolOffsetCurve::setOffsetForRubberBand( double offset, bool leftSide
       mRubberBand->setToGeometry( &mModifiedGeometry, sourceLayer );
     }
   }
+#else //GEOS_VERSION>=3.3
+  Q_UNUSED(offset);
+  Q_UNUSED(leftSide);
 #endif //GEOS_VERSION>=3.3
 }