Change the target to Windows XP-IA32: resolves the "not a valid Win32

application" error message (when run on XP) and reportedly will allow target
executables to run on non-SEE (pre-Pentium III) CPUs. Seriously, anyone really
running Windows XP on a Pentium II today? I guess it's possible <shrug> and we
really get little benefit from SSE in Synchronet.

I couldn't get Windows 2000 running in Hyper-V, so I guess Windows 2000 is
now officially unsupported by Synchronet (and long unsupported by Microsoft).

Thanks to Android8675 for the bug report and Rushfan for the solution tip.