Version numbers on libpq.dll

Hi!

We have a problem with the version numbers on libpq.dll. We have been
shipping the DLL through all betas and the RC with version number
"8.0.0.0". This has already caused several error reports both on the
mailinglists and on the pgFoundry bug trackers, because the file is not
replaced if you install two versions in parallell. Or if the file is in
use when installing a newer version. The installer will correctly check
the version number and determine that the file has not been updated.

In order for installation to work correctly, everytime there is a change
to the DLL the version number has to increase. Now, we certainly don't
need to bother with that between releases, but once a release (IMHO,
*including* beta or rc releases) it has to be bumped. We expecially need
it bumped when we go to release, otherwise people *will* end up running
their 8.0 release servers with pre-release libpq.dll.

Each of the numbers in the version number is a 16 bit integer. We are
already using the first three for the "normal" version number
(8.0.0/8.0.1 etc). The easiest way would be to simply have the fourth
number bumped up by one every time a new release is tagged. It can be
reset to zero whenever the file is changed into a new version (when the
first three change).

Could this be added to the "release tagging/building" checklist?
(affected file is src/interfaces/libpq/libpq.rc, several locations in
the file)

Another option would be to generate this automatically at build time.
Not sure how to do that really - I've been using subversion repository
versions there in some other projects, but since there is not a single
file building the DLL we can't do that with cvs, right? It might also
give some very interesting (heh) results in different branches etc.

Note! This is *only* necessary for libpq.dll, since that's the only one
we drop in SYSTEM32. The others can live side-by-side. It would be nice
to have the increasing between all releases just to be sure, but not at
all as important.

Hoping to get this in before 8.0.0, since it's not an actual code
change, and we *will* get a lot of bug reports if we don't get it fixed.

//Magnus