This isn't really necessary for our own code, because we use a .DEF file
in MSVC builds (see gendef.pl), or --export-all-symbols in MinGW and
Cygwin builds, to ensure that all global symbols in loadable modules
will be exported on Windows.  However, third-party authors might use
different build processes that need this marker, and it's harmless
enough for our own builds.

To some extent, this is an oversight in commit e7128e8d, so back-patch
to 9.4 where that was added.

Laurenz Albe

Discussion: <A737B7A37273E048B164557ADEF4A58B539300BD@ntex2010a.host.magwien.gv.at>