Drop support for long-obsolete versions of Windows
When we started writing Tor, Windows 98 was still a going concern. Now... it is less so.
We should identify and drop support code for all windows versions before Windows XP. This is mainly going to be a matter of identifying cases where we use LoadLibrary and GetProcAddress to find always-present-functions in always-present DLLs, and looking for opportunities to move from old busted APIs to fresh new ones.
(Dropping support for windows XP is a separate ticket.)