windows: fix test linking

[miriameng]

Fix

    test_undo_history.obj : error LNK2019: unresolved external symbol "public: __cdecl
     lfs::vis::op::TensorUndoEntry::TensorUndoEntry(...)"
    test_undo_history.obj : error LNK2019: unresolved external symbol "public: void __cdecl
     lfs::vis::op::TensorUndoEntry::captureAfter(void)"
    test_undo_history.obj : error LNK2019: unresolved external symbol "public: __cdecl
     lfs::vis::op::CropBoxUndoEntry::CropBoxUndoEntry(...)"
    test_undo_history.obj : error LNK2019: unresolved external symbol "public: __cdecl
     lfs::vis::op::EllipsoidUndoEntry::EllipsoidUndoEntry(...)"
    test_undo_history.obj : error LNK2019: unresolved external symbol "public: __cdecl
     lfs::vis::op::PropertyChangeUndoEntry::PropertyChangeUndoEntry(...)"
   
    C:\...\lichtfeld_tests.exe : fatal error LNK1120: 12 unresolved externals

[MrNeRF]

Weird that it pops up for you. The nightly Windows build is ok!

[miriameng]

If we can figure out a way to compile unit tests in CI we will see the same error

Aka #685

[MrNeRF]

Yeah, I still don't have an infrastructure sponsor. Hopefully soon