Re: plpgsql_check_function - rebase for 9.3

I wrote:
> [ pokes around... ] Hm, it appears that that does work on Linux,
> because for some reason we're specifying RTLD_GLOBAL to dlopen().
> TBH that seems like a truly horrid idea that we should reconsider.

A bit of research in the archives revealed that we're using it because
back in 2001, the lame hack that then passed for a shared-library
version of python required it:
http://www.postgresql.org/message-id/Pine.LNX.4.30.0105121914200.757-100000@peter.localdomain

There was subsequent discussion of removing it, because reportedly now
(a) that's no longer the case, and (b) we need to get rid of it to allow
plpython2 and plpython3 to coexist in one session. See for instance:
http://www.postgresql.org/message-id/1277506674.5356.27.camel@vanquo.pezone.net

Nothing's been done about that yet, but I think that assuming that we'll
be using RTLD_GLOBAL forever would be foolish.

regards, tom lane