win: Add implementation of system_snapshot for Windows

compat/win/winnt.h

Index: compat/win/winnt.h
diff --git a/compat/win/sys/time.h b/compat/win/winnt.h
similarity index 56%
copy from compat/win/sys/time.h
copy to compat/win/winnt.h
index 46bdef2a3810669fcf310d9d8a29a29980c3c894..2c5ac662108dde44a343c639eb46a32d546baad7 100644
--- a/compat/win/sys/time.h
+++ b/compat/win/winnt.h
@@ -12,12 +12,21 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#ifndef CRASHPAD_COMPAT_WIN_SYS_TIME_H_
-#define CRASHPAD_COMPAT_WIN_SYS_TIME_H_
+#ifndef CRASHPAD_COMPAT_WIN_WINNT_H_
+#define CRASHPAD_COMPAT_WIN_WINNT_H_
 
-struct timeval {
-  long tv_sec;
-  long tv_usec;
+// https://msdn.microsoft.com/en-us/library/windows/desktop/aa373184.aspx:
+// "Note that this structure definition was accidentally omitted from WinNT.h."
+struct PROCESSOR_POWER_INFORMATION {
+  ULONG Number;
+  ULONG MaxMhz;
+  ULONG CurrentMhz;
+  ULONG MhzLimit;
+  ULONG MaxIdleState;
+  ULONG CurrentIdleState;
 };
 
-#endif  // CRASHPAD_COMPAT_WIN_SYS_TIME_H_
+// include_next <winnt.h>
+#include <../um/winnt.h>
+
+#endif  // CRASHPAD_COMPAT_WIN_WINNT_H_