y2038: Convert gai_suspend to support 64 bit time

y2038: Convert gai_suspend to support 64 bit time

This change uses (in gai_misc.h):
- __futex_abstimed_wait64 (instead of futex_reltimed_wait)
- __futex_abstimed_wait_cancellable64
    	(instead of futex_reltimed_wait_cancellable)
        from ./sysdeps/nptl/futex-helpers.h

The gai_suspend() accepts relative timeout, which then is converted to
absolute one.

The i686-gnu port (HURD) do not define DONT_NEED_GAI_MISC_COND and as it
doesn't (yet) support 64 bit time it uses not converted
pthread_cond_timedwait().

The __gai_suspend() is supposed to be run on ports with __TIMESIZE !=64 and
__WORDSIZE==32. It internally utilizes __gai_suspend_time64() and hence the
conversion from 32 bit struct timespec to 64 bit one is required.

For ports supporting 64 bit time the __gai_suspend_time64() will be used
either via alias (to __gai_suspend when __TIMESIZE==64) or redirection
(when -D_TIME_BITS=64 is passed).

Build tests:
./src/scripts/build-many-glibcs.py glibcs

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>