VS2013: Prefer it over VS2012 and VS2010

The preference for compiler picking on Windows is:

1. vs2012
2. vs2010
3. vs2013

Because vs2013 was considered as unsupported compiler the only
option to acivate is to provide additional option to the autogen:

  --with-visual-studio=2013

Now, that vs2013 is up and running change the preference order and
pick the newest installed compiler.

Change-Id: I76412b9a1bd9514904bbcca99230896add0424f1
Reviewed-on: https://gerrit.libreoffice.org/10154
Reviewed-by: Thomas Arnhold <thomas@arnhold.org>
Tested-by: Thomas Arnhold <thomas@arnhold.org>