Fix some Win32 issues related to CAFS.

[KineticTheory]

Background

• CAFS stopped working recently for one client project. The main issue is that FindMPI was failing for a MInGW Makefile project spawned from a MSVC project. It is unclear what changed to cause this UseCase to fail, but it is likely that updating the CMake version was the issue.
• A new warning LNK4099 is also being issued when pdb files for TPLs aren't found. I will suppress this warning as a link flag.

Description of changes

• When defining an import library as used by CAFS, look for the lib in the project build directory, but look for the dll in the ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}.
• When setting up C4 variables, allow MPI to remain active if either MPI_CXX_FOUND or MPI_C_FOUND are true. This allows cmake projects that use C but not C++ to work properly.

Status

• Reference:
  • Pre-Merge Code Review
  • CDash Status
• Checks
  • Travis CI checks pass
  • Code coverage does not decrease
  • Valgrind test passes
  • Toss3 checks pass
  • Trinitite checks pass
  • Code reviewed/approved, sufficient DbC checks, testing, documentation

[KineticTheory]

@alexrlongne This one can also be merged when you have time to look at it.