C++: Remove 'using ::timeval' from ctime. struct timeval was recently move to...

C++: Remove 'using ::timeval' from ctime.  struct timeval was recently move to sys/time.h where it belongs.  Now there are problems when it is referenced in ctime.  Fixed by just removing it from ctime.  Is that correct?  or should ctime include sys/time.h?  Noted by David Sidrane