Move from GModule to libdl for loading libraries on all platforms. This is necessary due to a macOS bug where dyld uses the incorrect @loader_path value for RPATH entries, and fails to find libsoup. More details here: https://gitlab.freedesktop.org/gstreamer/gstreamer/-/issues/1171#note_2290789 Fixes https://gitlab.freedesktop.org/gstreamer/gstreamer/-/issues/3792 Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/7635>