...that had been removed with 28b4f4ae "Get rid
of Windows .def files in setup_native, use __declspec(dllexport)".  Looks like
for 32-bit builds, the .def file EXPORTS are still needed to avoid __stdcall's
_...@NN symbol decoration (and for 64-bit builds __stdcall is effectively
ignored, so the removed .def files didn't make a difference there).

This is only a partial revert of 28b4f4ae, the
addition of __declspec(dllexport) for the benefit of loplguin:external should
still be fine.

Change-Id: I76a1a3f4671824367bab495afeba291c0340108d
Reviewed-on: https://gerrit.libreoffice.org/61047
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>