Bump minimum MSVC version to 2017

Bump minimum MSVC version to 2017

On this platform, we should generally support only the latest version
of the various tools. It is not widely used by GROMACS users, and
fairly easy for them to install a new or upgraded version, so we
should generally prefer that GROMACS developers are less
inconvenienced in Jenkins by ongoing issues in the quality and
completeness of the implementation of MSVC.

MSVC support for attributes requires compilation in C++17 mode.
That's probably related to the way C++17 requires that unknown
attributes do not cause compilation to fail.

Change-Id: Icca6f537374fd88888a86152388f574ef14912ed