coredump filter: fix stack overflow with =all

coredump filter: fix stack overflow with =all

We translate 'all' to UNIT64_MAX, which has a lot more 'f's. Use the
helper macro, since a decimal uint64_t will always be >> than a hex
representation.

root@image:~# systemd-run -t --property CoredumpFilter=all ls /tmp
Running as unit: run-u13.service
Press ^] three times within 1s to disconnect TTY.
*** stack smashing detected ***: terminated
[137256.320511] systemd[1]: run-u13.service: Main process exited, code=dumped, status=6/ABRT
[137256.320850] systemd[1]: run-u13.service: Failed with result 'core-dump'.