[wpiutil] Get more precise system time on Windows

[PeterJohnson]

Windows 8 added GetSystemTimePreciseAsFileTime().

[calcmogul]

Are the other two instances relevant?

wpinet/src/main/native/thirdparty/libuv/src/win/util.cpp
1827:  GetSystemTimeAsFileTime(&file_time);

wpinet/src/main/native/thirdparty/libuv/src/win/fs.cpp
1162:  GetSystemTimeAsFileTime(&ft);

wpiutil/src/main/native/cpp/timestamp.cpp
123:  GetSystemTimeAsFileTime(&ft);

[PeterJohnson]

I don't think we use the util.cpp one anywhere. We may touch the fs.cpp one when reading files? I don't think there's harm in switching them though?

[calcmogul]

I'll look at making those changes to libuv separately.