Location for pgstat.stat

Per this thread:
http://archives.postgresql.org/pgsql-general/2007-12/msg00255.php

it was pretty much (again, IIRC) concluded that we want "some better
way" to transfer the stats data.

But pending that we have that, how about we just move it into it's own
subdirectory? AFAICS that would be a simple change of two #defines
moving it from "global/pgstat.stat" to "pgstat/pgstat.stat" or something
like that. Might also need some code to create the directory if it
doesn't exist, but that shouldn't be hard.

This would make it possible to symlink or mount that directory off to a
ramdrive (for example).

It's not a perfect solution, but it would at least give a better tool
than we have today, no?

//Magnus