In order to make sure that LLVM continues to work on machines that do not have the Universal CRT yet,
we'll need to ship a copy of UCRT in the Windows installation package. Fortunately, CMake 3.6+ already
supports app-local deployment of UCRT dlls, we just need to turn this on.

Differential Revision: https://reviews.llvm.org/D29146

llvm-svn: 293373