This release series of GLib began using features that are provided in
the Windows 8 SDK and later for Visual Studio builds. This also means
that it is no longer possible to build GLib with Visual Studio 2008 nor
2010 since the Windows 8+ SDKs do not work with those compiler versions.
Mention that people that still need to use those Visual Studio versions
should continue sticking on to glib-2.66.x, and so remove the section
about the workarounds that need to be applied for Visual Studio 2008
builds, since they are no longer applicable.
