Fixing sizeof argument.

It wasn't a bug before, but it was still wrong.
First draft of mpsq qoq.
Freeing mpsc nodes for qoq.
Using 'custom' signalling for mpsc qoq.

The custom signalling is just bypassing the generic lock/signal mechanism
and just store the waiting processors directly in a list.

This also means the awakening responsibilities are explicit in the
queue.
Fixing randmat (others should be fixed as well).

This is only sort-of a fix, it's just so I don't double-lock things.
Statically allocate the sync closure.

Since we know it won't survive the sync area then we can just allocate
it on the stack of the client.
Cleaning up indentation in mpsc_blocking.c.