[CMake] Import/export issue with shared library

[Hauke Heibel]

Perfect, what you suggested works like a charm. Within a small macro I
am now running this code

set(EXPORT_TARGET_LIST ${ARGV})
foreach(TARGET_UID ${ARGV})
  get_target_property(IA ${TARGET_UID} "IMPORTED")
  if(IA)
    list(REMOVE_ITEM EXPORT_TARGET_LIST ${TARGET_UID})
  endif()
endforeach()

before the actual export which fixes the problem.

Thanks again!

Hauke