This is an old issue and not related to the build-infra project.

During a build on JPRT systems, something in the makefiles is creating directories in the root C drive area, namely: C:/rt C:/sdk C:/Release C:/sign

And the file:
   C:/vc100.pdb
is being created.

This is a bug in the makefiles somewhere.
I assume it is in the deploy or install repository.

-kto