build_system: added all headers to the EnTT target

CMakeLists.txt

@@ -132,6 +132,7 @@ if(ENTT_INCLUDE_HEADERS)
             $<BUILD_INTERFACE:${EnTT_SOURCE_DIR}/src/entt/core/fwd.hpp>
             $<BUILD_INTERFACE:${EnTT_SOURCE_DIR}/src/entt/core/hashed_string.hpp>
             $<BUILD_INTERFACE:${EnTT_SOURCE_DIR}/src/entt/core/ident.hpp>
+            $<BUILD_INTERFACE:${EnTT_SOURCE_DIR}/src/entt/core/iterator.hpp>
             $<BUILD_INTERFACE:${EnTT_SOURCE_DIR}/src/entt/core/memory.hpp>
             $<BUILD_INTERFACE:${EnTT_SOURCE_DIR}/src/entt/core/monostate.hpp>
             $<BUILD_INTERFACE:${EnTT_SOURCE_DIR}/src/entt/core/tuple.hpp>