Fix MSVC C++17 build

[illusion0001]

D:\a\goo-engine\goo-engine\source\blender\editors\object\object_constraint.cc(2288,15): error C7555: use of designated initializers requires at least '/std:c++20' [D:\a\goo-engine\build_windows_x64_vc17_Release\source\blender\editors\object\bf_editor_object.vcxproj]

[illusion0001]

I guess this would work too.

struct IDRelinkUserData userdata{};
userdata.src_object = reinterpret_cast<ID*>(obact);
userdata.dst_object = reinterpret_cast<ID*>(pose_ob);