They are components from VisualStudio proper. Probably derived from a quite old code base. On old code bases you easily have the situation that parts of it are licensed from other vendors or contractors. Digging through old contracts and history of the code can be a notable effort.

Microsoft did the digging with their C++ standard library, which is derived from Dinkum's STL.

I observed that a bit with Sun and Solaris/OpenSolaris where in the final release was one component missing.

So even with will this won't come for free.