(l2g_start): Pass a log file name to the valgrind wrapper.

(dbck_run): Ditto.
(spawn_lyskomd): New argument: log file name.  All callers
	updated.  Use the lyskomd.supp valgrind suppressions file.
	Pass --show-reachable=yes and a log file name to valgrind.
(check_valgrind): New arguments: logfile, need_leaks and need_errs.
	All callers updated.