Fix VS generator test build error
Fix VS generator test build error

Fixes an error building the new drreg test changes on VS generators.

Review-URL: https://codereview.appspot.com/268980043

AmesianX/dynamorio,code4bones/dynamorio,code4bones/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,code4bones/dynamorio,code4bones/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,code4bones/dynamorio