fix two buglets in breakpoint.c

fix two buglets in breakpoint.c

First, output_thread_groups leaks a cleanup along one return path.

Second, parse_cmd_to_aexpr could return without running its cleanups,
if there was an exception in a TRY_CATCH.

	* breakpoint.c (output_thread_groups, parse_cmd_to_aexpr): Call
	do_cleanups earlier.