Fix: bt2: int-to-pointer-cast warnings in SWIG utils functions

Fix: bt2: int-to-pointer-cast warnings in SWIG utils functions

  bt2/native_bt_wrap.c: In function ‘bt_py3_component_class_query’:
  bt2/native_bt_wrap.c:4453:12: warning: cast to pointer from integer of
    different size [-Wint-to-pointer-cast]
      *result = (void *) PyLong_AsUnsignedLongLong(py_results_addr);
               	 ^
  bt2/native_bt_wrap.c: In function ‘bt_py3_component_class_message_iterator_next’:
  bt2/native_bt_wrap.c:4697:3: warning: cast to pointer from integer of
    different size [-Wint-to-pointer-cast]
      (const bt_message *) PyLong_AsUnsignedLongLong(
      ^
  python-plugin-provider.c: In function ‘bt_plugin_from_python_plugin_info’:
  python-plugin-provider.c:341:18: warning: cast to pointer from integer of
    different size [-Wint-to-pointer-cast]
       comp_class = (bt_component_class *)

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Change-Id: I44d15e5d072d993776539eddae5f3e37c6161cac
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1162
CI-Build: Francis Deslauriers <francis.deslauriers@efficios.com>
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>