Update symbol name mangling
Compare changes
This avoids link errors in applications which depend on libPNG aside from the one in VTK, for example as bundled with OpenCV. Example error messages:
10>vtkpng-9.0d.lib(pngget.obj) : error LNK2005: png_get_eXIf already defined in libpngd.lib(pngget.obj) [M:\Dev\Plus\SP-VTK9\PlusLib-bin\src\PlusDataCollection\PlusVersion.vcxproj]
10>vtkpng-9.0d.lib(pngget.obj) : error LNK2005: png_get_eXIf_1 already defined in libpngd.lib(pngget.obj) [M:\Dev\Plus\SP-VTK9\PlusLib-bin\src\PlusDataCollection\PlusVersion.vcxproj]
10>vtkpng-9.0d.lib(pngset.obj) : error LNK2005: png_set_eXIf already defined in libpngd.lib(pngset.obj) [M:\Dev\Plus\SP-VTK9\PlusLib-bin\src\PlusDataCollection\PlusVersion.vcxproj]
10>vtkpng-9.0d.lib(pngset.obj) : error LNK2005: png_set_eXIf_1 already defined in libpngd.lib(pngset.obj) [M:\Dev\Plus\SP-VTK9\PlusLib-bin\src\PlusDataCollection\PlusVersion.vcxproj]
10>vtkpng-9.0d.lib(pngrutil.obj) : error LNK2005: png_handle_eXIf already defined in libpngd.lib(pngrutil.obj) [M:\Dev\Plus\SP-VTK9\PlusLib-bin\src\PlusDataCollection\PlusVersion.vcxproj]
10>vtkpng-9.0d.lib(pngrutil.obj) : error LNK2005: png_check_chunk_length already defined in libpngd.lib(pngrutil.obj) [M:\Dev\Plus\SP-VTK9\PlusLib-bin\src\PlusDataCollection\PlusVersion.vcxproj]
10>vtkpng-9.0d.lib(pngwutil.obj) : error LNK2005: png_write_eXIf already defined in libpngd.lib(pngwutil.obj) [M:\Dev\Plus\SP-VTK9\PlusLib-bin\src\PlusDataCollection\PlusVersion.vcxproj]