message: Keep default -fvisibity if static
  otherwise link to static DataFrame may report warnings:
  ld: warning: direct access in function '___cxx_global_var_init' from file 'libDataFrame.a(DateTime.cc.o)' to global weak symbol 'guard variable for hmdf::DateTime::dt_init_'
diff: @@ -42,7 +42,6 @@ target_compile_features(DataFrame PUBLIC cxx_std_17)
  target_compile_definitions(DataFrame
  PUBLIC
  $<$<CXX_COMPILER_ID:MSVC>:_USE_MATH_DEFINES>
  - $<$<BOOL:${BUILD_SHARED_LIBS}>:HMDF_SHARED>
  )
  target_compile_options(DataFrame
  PRIVATE
  @@ -56,12 +55,19 @@ target_compile_options(DataFrame
  )
  set_target_properties(DataFrame
  PROPERTIES
  - CXX_VISIBILITY_PRESET hidden
  - VISIBILITY_INLINES_HIDDEN ON
  VERSION ${PROJECT_VERSION}
  SOVERSION ${PROJECT_VERSION_MAJOR}
  )
  +if(BUILD_SHARED_LIBS)
  + set_target_properties(DataFrame
  + PROPERTIES
  + CXX_VISIBILITY_PRESET hidden
  + VISIBILITY_INLINES_HIDDEN ON
  + )
  + target_compile_definitions(DataFrame PUBLIC HMDF_SHARED)
  +endif()
  +
  target_link_libraries(DataFrame
  INTERFACE
  Threads::Threads
  