cmake HAS_PRIVATE_HEADERS examples

TeXworks/texworks modules/QtPDF/CMakeLists.txt :309 

get_target_property(POPPLER_HAS_XPDF Poppler::poppler HAS_PRIVATE_HEADERS)

TeXworks/texworks modules/QtPDF/CMake/Modules/FindPoppler.cmake :201 

set_target_properties(Poppler::poppler PROPERTIES
        INTERFACE_INCLUDE_DIRECTORIES "${Poppler_PRIVATE_INCLUDE_DIR}"
        HAS_PRIVATE_HEADERS On
      )