Specifically, add support for the IPC_INFO, SEM_INFO, and SEM_STAT
semctl(2) operations, similar to how information about shared memory
is already exposed as well. The MINIX3 ipcs(1) utility already had
support for these operations, and can now actually use them, too.
Change-Id: Ice5a02e729bf6df6aa8fab76e854808adc04dae3