Editor plugin trying to process SkeletalMeshes

I have an editor plugin that scans for my custom actor class objects, grabs their skeletalmeshcomponent, and then iterates over the mesh bones to generate box collision components. I first tried to call into MeshUtilities, the way generating physics assets does, but ran into problems getting it to build. So, I switched to copying the relevant chunks of code out of MeshUtilities and SkeletalMeshTools. Now, when I build, the linker spits out an error :

unresolved external symbol “__declspec(dllimport) union __m128 const GVectorPackingConstants” (_imp?GVectorPackingConstants@@3T_m128@@B)

I’m a little rusty with C++, but this used to mean you were missing a library file in your library paths. Digging through code to see what header I need to #include hasn’t been fruitful. Help?