This addresses several build warnings mostly for the Windows and debug builds.
Currently there is 1 remaining linker warning in the debug build. the "full" configuration builds cleanly. As I'm unfamiliar with the CMake and the VS linker I don't know how to resolve the remaining warning.
I began looking into pushing changes upstream, and found many of the /extern libraries we use seem to have diverged from released versions. Still investigating while changes may be applicable to existing versions. We probably want to update many/most of these when 2.81 rolls around.