Valgrind shows leak in rcutils_load_shared_library

Apologies if this is tracked somewhere already, or addressed in a previous version. I'm still getting oriented here...

This happens on a recent-ish (~2-3 weeks old) ros2_rolling clone. I hit it while debugging some odd library unload behavior in Nav2's planner_server. The command to start it was:

valgrind --leak-check=full --num-callers=60 /home/mbryan/Projects/ros/navigation2/install/nav2_planner/lib/nav2_planner/planner_server --ros-args --log-level info --ros-args -r __node:=planner_server -p use_sim_time:=True --params-file /tmp/tmpm5wzacln -r /tf:=tf -r /tf_static:=tf_static

NOTE: that path points to my navigation2 clone. My built ros2_rolling clone is in my path (see bottom stack frame below).

==49974== 
==49974== HEAP SUMMARY:
==49974==     in use at exit: 224,129 bytes in 761 blocks
==49974==   total heap usage: 92,290 allocs, 91,529 frees, 19,064,079 bytes allocated
==49974== 
==49974== 64 bytes in 1 blocks are definitely lost in loss record 50 of 172
==49974==    at 0x4852899: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==49974==    by 0x400F21D: malloc (rtld-malloc.h:56)
==49974==    by 0x400F21D: resize_scopes (dl-open.c:295)
==49974==    by 0x400F21D: dl_open_worker_begin (dl-open.c:707)
==49974==    by 0x5DDAC27: _dl_catch_exception (dl-error-skeleton.c:208)
==49974==    by 0x400DF99: dl_open_worker (dl-open.c:782)
==49974==    by 0x5DDAC27: _dl_catch_exception (dl-error-skeleton.c:208)
==49974==    by 0x400E34D: _dl_open (dl-open.c:883)
==49974==    by 0x5CF66BB: dlopen_doit (dlopen.c:56)
==49974==    by 0x5DDAC27: _dl_catch_exception (dl-error-skeleton.c:208)
==49974==    by 0x5DDACF2: _dl_catch_error (dl-error-skeleton.c:227)
==49974==    by 0x5CF61AD: _dlerror_run (dlerror.c:138)
==49974==    by 0x5CF6747: dlopen_implementation (dlopen.c:71)
==49974==    by 0x5CF6747: dlopen@@GLIBC_2.34 (dlopen.c:81)
==49974==    by 0x4C5CF02: rcutils_load_shared_library (in /home/mbryan/Projects/ros/ros2_rolling/install/rcutils/lib/librcutils.so)
==49974==    by 0x63EB667: rcpputils::SharedLibrary::SharedLibrary(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) (in /home/mbryan/Projects/ros/ros2_rolling/install/rcpputils/lib/librcpputils.so)
==49974==    by 0x6CCD633: rosidl_message_type_support_t const* rosidl_typesupport_c::get_typesupport_handle_function<rosidl_message_type_support_t>(rosidl_message_type_support_t const*, char const*) (in /home/mbryan/Projects/ros/ros2_rolling/install/rosidl_typesupport_c/lib/librosidl_typesupport_c.so)
==49974==    by 0x6CCD3FF: rosidl_typesupport_c__get_message_typesupport_handle_function (in /home/mbryan/Projects/ros/ros2_rolling/install/rosidl_typesupport_c/lib/librosidl_typesupport_c.so)
==49974==    by 0x6CAD6D0: get_message_typesupport_handle (in /home/mbryan/Projects/ros/ros2_rolling/install/rosidl_runtime_c/lib/librosidl_runtime_c.so)
==49974==    by 0x7566280: rmw_fastrtps_cpp::create_publisher(CustomParticipantInfo const*, rosidl_message_type_support_t const*, char const*, rmw_qos_profile_s const*, rmw_publisher_options_s const*, bool, bool) (in /home/mbryan/Projects/ros/ros2_rolling/install/rmw_fastrtps_cpp/lib/librmw_fastrtps_cpp.so)
==49974==    by 0x7585B31: rmw_create_publisher (in /home/mbryan/Projects/ros/ros2_rolling/install/rmw_fastrtps_cpp/lib/librmw_fastrtps_cpp.so)
==49974==    by 0x669E915: rmw_create_publisher (in /home/mbryan/Projects/ros/ros2_rolling/install/rmw_implementation/lib/librmw_implementation.so)
==49974==    by 0x642D575: rcl_publisher_init (in /home/mbryan/Projects/ros/ros2_rolling/install/rcl/lib/librcl.so)
==49974==    by 0x6428499: rcl_logging_rosout_init_publisher_for_node (in /home/mbryan/Projects/ros/ros2_rolling/install/rcl/lib/librcl.so)
==49974==    by 0x642B72A: rcl_node_init (in /home/mbryan/Projects/ros/ros2_rolling/install/rcl/lib/librcl.so)
==49974==    by 0x567587B: rclcpp::node_interfaces::NodeBase::NodeBase(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::shared_ptr<rclcpp::Context>, rcl_node_options_s const&, bool, bool, std::shared_ptr<rclcpp::CallbackGroup>) (in /home/mbryan/Projects/ros/ros2_rolling/install/rclcpp/lib/librclcpp.so)
==49974==    by 0x4B3283E: rclcpp_lifecycle::LifecycleNode::LifecycleNode(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, rclcpp::NodeOptions const&, bool) (in /home/mbryan/Projects/ros/ros2_rolling/install/rclcpp_lifecycle/lib/librclcpp_lifecycle.so)
==49974==    by 0x6268DCE: nav2_util::LifecycleNode::LifecycleNode(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, rclcpp::NodeOptions const&) (in /home/mbryan/Projects/ros/navigation2/build/nav2_util/src/libnav2_util_core.so)
==49974==    by 0x48E85D4: nav2_planner::PlannerServer::PlannerServer(rclcpp::NodeOptions const&) (in /home/mbryan/Projects/ros/navigation2/build/nav2_planner/libplanner_server_core.so)
==49974==    by 0x10E553: void __gnu_cxx::new_allocator<nav2_planner::PlannerServer>::construct<nav2_planner::PlannerServer>(nav2_planner::PlannerServer*) [clone .isra.0] (in /home/mbryan/Projects/ros/navigation2/build/nav2_planner/planner_server)
==49974==    by 0x10E702: std::__shared_ptr<nav2_planner::PlannerServer, (__gnu_cxx::_Lock_policy)2>::__shared_ptr<std::allocator<nav2_planner::PlannerServer>>(std::_Sp_alloc_shared_tag<std::allocator<nav2_planner::PlannerServer> >) (in /home/mbryan/Projects/ros/navigation2/build/nav2_planner/planner_server)
==49974==    by 0x10D80B: main (in /home/mbryan/Projects/ros/navigation2/build/nav2_planner/planner_server)

Minor leak; seems low priority. Please advise if this needs punting over to another repo.

Not sure if it's related, but I see this log line in the tests I'm running; putting it here for FYI:

[228.584185] (nav2_regulated_pure_pursuit_controller) StdoutLine: {'line': b'6: Warning: class_loader.ClassLoader: SEVERE WARNING!!! Attempting to unload library while objects created by this loader exist in the heap! You should delete your objects before attempting to unload the library or destroying the ClassLoader. The library will NOT be unloaded.\n'}

Start at rcutils_load_shared_library and reproduce the reported Valgrind command, then trace the allocation through the shared-library loading path shown in the stack trace. Compare the result with the class_loader unload warning and determine whether rcutils owns the leak or whether it belongs in another repository; done requires a confirmed cause and an appropriate fix or handoff.