Introduce time64 support.

Introduce time64 support.

This patch introduces *time64 syscalls support for uClibc-ng.
Currently the redirection of syscalls to their *time64
analogs is fully supported for 32bit ARM (ARMv5, ARMv6, ARMv7).
The main changes that take effect when time64 feature is enabled are:
- sizeof(time_t) is 8.
- There is a possibility os setting date beyond year 2038.
- some syscalls are redirected:
clock_adjtime -> clock_adjtime64
clock_getres -> clock_getres_time64
clock_gettime -> clock_gettime64
clock_nanosleep -> clock_nanosleep_time64
clock_settime -> clock_settime64
futex -> futex_time64
mq_timedreceive -> mq_timedreceive_time64
mq_timedsend -> mq_timedsend_time64
ppoll -> ppoll_time64
pselect6 -> pselect6_time64
recvmmsg -> recvmmsg_time64
rt_sigtimedwait -> rt_sigtimedwait_time64
sched_rr_get_interval -> sched_rr_get_interval_time64
semtimedop -> semtimedop_time64
timer_gettime -> timer_gettime64
timer_settime -> timer_settime64
timerfd_gettime -> timerfd_gettime64
timerfd_settime -> timerfd_settime64
utimensat -> utimensat_time64.

- settimeofday uses clock_settime (like in glibc/musl).
- gettimeofday uses clock_gettime (like in glibc/musl).
- nanosleep uses clock_nanosleep (like in glibc/musl).

- There are some fixes in data structures used by libc and kernel
for correct data handling both with and without enabled time64 support.

Signed-off-by: Dmitry Chestnykh <dm.chestnykh@gmail.com>