Fix include and source file distribution issues

Signed-off-by: Pierre R. Mai <pmai@pmsf.de>

Author: pmai

CMakeLists.txt

@@ -95,6 +95,7 @@ if(BUILD_FLATBUFFER)
                    EXCLUDE_FROM_ALL)
   file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/descriptor.fbs" "namespace osi3;")
   file(MAKE_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/include")
+  list(APPEND FLAT_FBS "${CMAKE_CURRENT_BINARY_DIR}/descriptor.fbs")
   foreach (proto ${OSI_PROTO_FILES})
     get_filename_component(proto_base ${proto} NAME_WE)
     set(fbs "${proto_base}.fbs")
@@ -124,7 +125,6 @@ if(BUILD_FLATBUFFER)
 
   add_custom_target(${PROJECT_NAME}_fbs_build ALL DEPENDS "${FLAT_HEADERS}")
   add_library(${PROJECT_NAME}_fbs INTERFACE)
-  target_sources(${PROJECT_NAME}_fbs INTERFACE "$<BUILD_INTERFACE:${FLAT_HEADERS}>")
   target_include_directories(${PROJECT_NAME}_fbs INTERFACE $<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}/include/>)
   target_include_directories(${PROJECT_NAME}_fbs SYSTEM INTERFACE $<INSTALL_INTERFACE:$<INSTALL_PREFIX>/include>)
   target_link_libraries(${PROJECT_NAME}_fbs INTERFACE flatbuffers)