systemd-coredump: Ignore coredumps larger than COREDUMP_MAX

Currently this check happens when the coredump has been collected in
it's entirety and being received by journald. this is not ideal
behaviour when the crashing process is consuming significant percentage
of physical memory such as a large instance of firefox or a java
application.
systemd-coredump: Log crashes without coredumps on failure

Make a best-effort attempt to store information about crashes during
failure, currently if these are encountered the crash is completely
silenced.

ideally coredumpctl would show if a coredump is available.