Proposal - increase SYSV SEMMNI and SEMMNS

[Ivan Voras]

Currently, the defaults are:

kern.ipc.semmni: 10
kern.ipc.semmns: 60

but there are several nontrivial pieces of software that would use much
more; two examples are PostgreSQL (the database) and Mono (the .net clone).

I'd like to increase these defaults to:

kern.ipc.semmni: 50
kern.ipc.semmns: 300

If I'm reading it correctly, each semaphore takes around 12 bytes (times
SEMMNS), allocated with kernel malloc at boot time.

This change is not as critical as before since both are now loader
tunables, but increasing the defaults would be a convenience move, to
save some reconfiguration-and-reboot hassle when installing software.