In QVTKWidgetPlugin: CMAKE_DEBUG_POSTFIX is not taken into account on install

This issue was created automatically from an original Mantis Issue. Further discussion may take place here.

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I set CMAKE_DEBUG_POSTFIX to "d" to install both release and debug libraries into the same location on Windows. When building the INSTALL-target in the Debug-configuration it fails because PluginInstall.cmake.in tries to install a non-existing file (it does not append the debug postfix).

I used VTK 6.1.0.