getrusage-windows: getrusage() for Windows.

getrusage-windows: getrusage() for Windows.

We use getrusage mainly to get user CPU time and system CPU time.
Windows has a GetProcessTimes and GetThreadTimes that does the
same job. So use them.

We also use getrusage to get page faults. Use GetProcessMemoryInfo()
for that.

We also get number of context switches, block i/o times and use it for
debug information when we wake up from poll_block late. I haven't found
functions for that in Windows. We only use it for debug information, so
it should be okay not implementing it.

Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>
Co-authored-by: Linda Sun <lsun@vmware.com>
Signed-off-by: Linda Sun <lsun@vmware.com>
Acked-by: Ben Pfaff <blp@nicira.com>