create imported interface library for coVRAudio

so that it's possible to depend on additional libraries, such as GLM

Author: aumuell

cmake/FindCOVER.cmake

@@ -65,7 +65,9 @@ mark_as_advanced(COVER_LIBRARY
 
 if(COVER_FOUND)
    set(COVER_INCLUDE_DIRS ${COVER_INCLUDE_DIR} ${COVISE_INCLUDE_DIR})
-   target_link_libraries(${COVER_AUDIO_LIBRARY} INTERFACE glm::glm)
+   add_library(cover::audio INTERFACE IMPORTED)
+   #set_target_properties(cover::audio PROPERTIES IMPORTED_LOCATION ${COVER_AUDIO_LIBRARY})
+   target_link_libraries(cover::audio INTERFACE ${COVER_AUDIO_LIBRARY} glm::glm)
 endif()
 
 MACRO(COVER_ADD_PLUGIN targetname)
@@ -125,7 +127,7 @@ MACRO(COVER_ADD_PLUGIN_TARGET targetname)
   ENDIF()
 
   TARGET_LINK_LIBRARIES(${targetname} ${COVER_PLUGINUTIL_LIBRARY}
-     ${COVER_LIBRARY} ${COVER_AUDIO_LIBRARY} ${COVER_VRUI_LIBRARY} ${COVER_OSGVRUI_LIBRARY} ${COVER_CONFIG_LIBRARY}
+     ${COVER_LIBRARY} cover::audio ${COVER_VRUI_LIBRARY} ${COVER_OSGVRUI_LIBRARY} ${COVER_CONFIG_LIBRARY}
      ${COVISE_VRBCLIENT_LIBRARY} ${COVISE_CONFIG_LIBRARY} ${COVISE_UTIL_LIBRARY} ${OPENSCENEGRAPH_LIBRARIES})
 
   qt_use_modules(${targetname} Core)