build: remove VS 2013 switch from vcbuild.bat

Support for Visual Studio 2013 has officially been dropped, remove the
build option for that compiler.

PR-URL: https://github.com/nodejs/node/pull/8067
Refs: https://github.com/nodejs/node/issues/7484
Refs: https://github.com/nodejs/node/pull/8049


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Joao Reis <reis@janeasystems.com>