The virSysinfoIsEqual method was mistakenly inside a #ifndef WIN32
conditional.

The existing virSysinfoFormat is also stubbed out on Win32, even
though the code works without any trouble. This breaks XML output
on Win32, so the stub is removed.

virsh migrate mistakenly had some variables inside the conditional

* src/util/sysinfo.c: Build virSysinfoIsEqual on Win32 and remove
  Win32 stub for virSysinfoFormat
* tools/virsh.c: Fix variable declaration on Win32