terminal/subterm: use usec_t instead of "unsigned long"

Avoid hard-coding "unsigned long" and use the usec_t type defined in
src/shared.
barrier: convert msecs to usecs in test-code

Avoid using msecs in favor of usec_t. This is more consistent with the
other parts of systemd and avoids the confusion between msec and usec. We
always use usecs, end of story.
time-util: add and use USEC/NSEC_INFINIY
login: update systemd-user PAM configuration file
udevd: add --event-timeout commandline option

Some events take longer than the default 30 seconds. Killing those
events will leave the machine halfway configured.

Add a commandline option '--event-timeout' to handle these cases.
udev: unify event timeout handling
build-sys: remove systemd-coredumpctl symlink
udev: place opening { at the same line as the function declaration
factory: install minimal PAM and nsswitch config
test: test_tables - fix missing symbols when --gc-sections are not available
build-sys: add missing files for distcheck
barrier: fix race in test-code

The barrier_wait_next_twice* test-cases run:
  Parent:                             Child:
    set_alarm(10)                       sleep_for(1);
    ...                                 set_alarm(1);
    sleep_for(2)                        ...

Therefore, the parent exits after 2+ periods, the client's alarm fires
after 2+ periods. This race turns out to be lost by the child on other
machines, so avoid it by increasing the parent's sleep-interval to 4. This
way, the client has 2 periods to run the barrier test, which is far more
than enough.
resolve: add llmnr responder side for UDP and TCP

Name defending is still missing.
resolved: when resolving an address PTR record via llmnr, make a tcp connection by default
Update TODO
resolved: discard more invalid llmnr messages
resolved: re-add support for getting local domain from DHCP

When the code for generating resolv.conf was moved from networkd to
resolved the DHCP domain name code was dropped.