stasis: Fix for Doxygen.

include/asterisk/stasis.h

include/asterisk/stasis_app.h

include/asterisk/stasis_app_device_state.h

include/asterisk/stasis_app_playback.h

include/asterisk/stasis_app_recording.h

include/asterisk/stasis_app_snoop.h

include/asterisk/stasis_bridges.h

include/asterisk/stasis_channels.h

include/asterisk/stasis_internal.h

include/asterisk/stasis_message_router.h

include/asterisk/stasis_system.h

include/asterisk/stasis_test.h

main/stasis.c

main/stasis_bridges.c

main/stasis_cache.c

main/stasis_state.c

res/res_stasis_snoop.c

res/stasis/app.c

res/stasis/app.h

res/stasis/control.h