util/time: add util_time_sleep() for windows userspace

Somebody with a clue could probably do a better implemenation...

src/gallium/auxiliary/util/u_time.c

@@ -217,4 +217,13 @@ void util_time_sleep(unsigned usecs)
    } while(start <= curr && curr < end || 
 	   end < start && (curr < end || start <= curr));
 }
+#elif defined(PIPE_SUBSYSTEM_WINDOWS_USER)
+#include <unistd.h>
+#include <fcntl.h>
+ 
+
+void util_time_sleep(unsigned usecs)
+{
+   Sleep((usecs + 999)/ 1000);
+}
 #endif