Revert "Merge branch 'bugfix/register-target-instead-of-include-directory' into 'master'"

This reverts merge request !1457

cmake/modules/DuneModuleDependencies.cmake

@@ -200,6 +200,8 @@ macro(dune_process_dependency_macros)
         message(AUTHOR_WARNING "This needs to be removed!")
       endif()
 
+      # register dune module
+      dune_register_package_flags(INCLUDE_DIRS "${${_mod}_INCLUDE_DIRS}")
     endif()
   endforeach()
 endmacro(dune_process_dependency_macros)