[Toybox] Does anybody use ipcmk?

[Rob Landley]

toys/pending/ipcs.c and toys/pending/iprm.c will list and delete sysv
inter-process communication resources (shared memory, message queue, and
semaphore). But there's no equivalent way to create them, which makes tests hard
to do.

Ubuntu's command line has an ipcmk command from util-linux, but it's not in
posix (or in busybox).

Has anybody used this stuff much? (For shared memory segments I've just opened
/dev/shm files and deleted them when done, and that way I can lsof them to see
who's using what. I've installed packages that needed message queues and sysv
semaphores, but that was mostly in the context of "I need to enable this kernel
symbol or this thing won't work". )

I want to cleanup and promote these commands, but kinda need to be able to test
the results. I suspect I should do an ipcmk too, but since I'm not an existing
user of the command it's hard to be confident I've done it right...

Rob