Convert parser of struct timex to new mpers infrastructure

Convert parser of struct timex to new mpers infrastructure

* defs.h (adjtimex_modes, adjtimex_status): New xlat prototypes.
* print_timex.c (struct_timex): New typedef.  Mpersify it.
[IN_MPERS]: Do not include "xlat/adjtimex_modes.h"
and "xlat/adjtimex_status.h".
[SUPPORTED_PERSONALITIES > 1]: Remove.
(tprint_timeval): Remove.
(tprint_timex): Rename to print_timex.  Mpersify it.
* time.c (do_adjtimex): Rename tprint_timex to print_timex.
* tests/adjtimex.c: New file.
* tests/adjtimex.test: New test.
* tests/Makefile.am (check_PROGRAMS): Add adjtimex.
(TESTS): Add adjtimex.test.
* tests/.gitignore: Add adjtimex.