This shuts down the spawned builtin server process by sending it a
SIGTERM when the seat is closed.
This is probably trying to fix the same issue as 795cf169e779
("seatd: Shut down on client disconnect in builtin"), but I can't see
how this is supposed to work. AFAICS nothing defines LIBSEAT and I
don't see any way to distinguish between a real seatd server and the
builtin one at that spot in the code.
LIBSEAT is defined by meson when building libseat, see meson.build line
libseat_c_args = ['-DLIBSEAT=1']
The libseat builtin server is included directly into libseat itself
with that define set, while the seatd binary is built without that
Yea, I found that after I sent the patch and apparently 795cf169e779 is
even required for the subject patch to work as intended. I guess I need
to take a closer look again, except you might have some ideas on why
the shutdown isn't working as intended in my use case.
This is all separate from the newer seatd-launch procedure, which just
uses the seatd binary rather than building seatd into libseat itself.