Allow checking whether external lib is used

cmake/modules/3rdParty.cmake

@@ -44,6 +44,7 @@ if(NOT DEFINED THIRD_PARTY_MODULE_LOADED)
 
         # add library to list of libraries to link against when building dynamic libraries or applications
         if(${NAME}_STATIC_LIB AND (("${LINKAGE}" STREQUAL "AUTO_LINKAGE" AND ((NOT (${NAME}_DYNAMIC_LIB OR ${NAME}_SHARED_LIB)) OR (STATIC_LINKAGE AND "${META_PROJECT_TYPE}" STREQUAL "application") OR (STATIC_LIBRARY_LINKAGE AND ("${META_PROJECT_TYPE}" STREQUAL "" OR "${META_PROJECT_TYPE}" STREQUAL "library")))) OR ("${LINKAGE}" STREQUAL "STATIC")))
+            set(USE_${NAME} ON)
             set(USE_STATIC_${NAME} ON)
             list(APPEND LIBRARIES ${${NAME}_STATIC_LIB})
             if(${${NAME}_STATIC_LIB} IN_LIST META_PUBLIC_STATIC_LIB_DEPENDS)
@@ -53,6 +54,7 @@ if(NOT DEFINED THIRD_PARTY_MODULE_LOADED)
             endif()
             message(STATUS "Linking ${TARGET_PREFIX}${META_PROJECT_NAME}${TARGET_SUFFIX} statically against external library ${NAME} (${${NAME}_STATIC_LIB}).")
         elseif((${NAME}_DYNAMIC_LIB OR ${NAME}_SHARED_LIB) AND (("${LINKAGE}" STREQUAL "AUTO_LINKAGE") OR ("${LINKAGE}" STREQUAL "SHARED")))
+            set(USE_${NAME} ON)
             set(USE_SHARED_${NAME} ON)
             if(NOT ${NAME}_DYNAMIC_LIB)
                 set(${NAME}_DYNAMIC_LIB ${${NAME}_SHARED_LIB})