Print struct timeval consistently

Print struct timeval consistently

Use print_struct_timeval interface to print struct timeval.

* print_timeval.c (print_struct_timeval): New mpers printer.
* print_timex.c (print_timex): Use it.
* printrusage.c (printrusage): Likewise.
* v4l2.c (print_v4l2_buffer): Likewise.
* tests/getrusage.c (main): Print tv_sec and tv_usec fields as signed.
* tests/waitid.c (sprint_rusage): Likewise.

Suggested-by: Eugene Syromyatnikov <evgsyr@gmail.com>