message: Treat dataman plugins as proper module libs instead of shared
diff: # accompanying file Copyright.txt for details.
  #------------------------------------------------------------------------------#
  +set(dataman_targets)
  +
  add_library(dataman
  DataManBase.h DataManBase.cpp
  DataMan.h DataMan.cpp
  )
  target_include_directories(dataman PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
  target_link_libraries(dataman PRIVATE adios2sys)
  +list(APPEND dataman_targets dataman)
  +
  +# Add the dataman plugins as MODULE libraries instead of SHARED libraries.
  +# MODULE libraries are designed to be plugins, i.e. shared libs that nobody
  +# else links to.
  -add_library(cacheman SHARED CacheMan.h CacheMan.cpp)
  +add_library(cacheman MODULE CacheMan.h CacheMan.cpp)
  target_link_libraries(cacheman PRIVATE dataman)
  +list(APPEND dataman_targets cacheman)
  install(
  - TARGETS dataman cacheman EXPORT adios2
  + TARGETS ${dataman_targets} EXPORT adios2
  RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
  LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
  ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
  