timeval: Use high resolution timestamps on Windows

- Use QueryPerformanceCounter on Windows Vista+

There is confusing info floating around that QueryPerformanceCounter
can leap etc, which might have been true long time ago, but no longer
the case nowadays (perhaps starting from WinXP?). Also, boost and
std::chrono::steady_clock use QueryPerformanceCounter in a similar way.

Prior to this change GetTickCount or GetTickCount64 was used, which has
lower resolution. That is still the case for <= XP.

Fixes https://github.com/curl/curl/issues/3309
Closes https://github.com/curl/curl/pull/3318