win: fix custom actions on Visual Studio != 2013

The original change that added support for running custom actions during
the install process (e7c84f82

) assumed
that Visual Studio 2013 is used to generate the installer file.

However, that is not always the case, and older versions of Visual
Studio should allow users to generate Windows installer files. This
change makes the custom actions visual studio project use the visual
studio version that is found by vcbuild.bat.

Reviewed-By: João Reis <reis@janeasystems.com>
PR-URL: https://github.com/joyent/node/pull/25569