Re: Add PGDLLEXPORT to PG_FUNCTION_INFO_V1

I wrote:
> Well, the buildfarm doesn't like that even a little bit. It seems that
> the MSVC compiler does not like seeing both "extern Datum foo(...)" and
> "extern PGDLLEXPORT Datum foo(...)", so anything that had an extern in
> a .h file is failing. There is also quite a bit of phase-of-the-moon
> behavior in here, because in some cases some functions are raising errors
> and others that look entirely the same are not.

I take back the latter comment --- I was comparing HEAD source code
against errors reported on back branches, and at least some of the
discrepancies are explained by additions/removals of separate "extern"
declarations. But still, if we want to do this we're going to need to
put PGDLLEXPORT in every V1 function extern declaration. We might be
able to remove some of the externs as unnecessary instead, but any way
you slice it it's going to be messy.

For the moment I've reverted the change.

regards, tom lane