Add support for io_pgetevents_time64 syscall

Add support for io_pgetevents_time64 syscall

32-bit architectures that are y2038 safe don't include syscalls that use
32-bit time_t. Instead these architectures have suffixed syscalls that
always use a 64-bit time_t. In the case of the io_getevents syscall the
syscall has been replaced with the io_pgetevents_time64 syscall instead.

This patch changes the io_getevents() function to use the correct
syscall based on the avaliable syscalls and the time_t size. We will
only use the new 64-bit time_t syscall if the architecture is using a
64-bit time_t. This is to avoid having to deal with 32/64-bit
conversions and relying on a 64-bit timespec struct on 32-bit time_t
platforms. As of Linux 5.3 there are no 32-bit time_t architectures
without __NR_io_getevents. In the future if a 32-bit time_t architecture
wants to use the 64-bit syscalls we can handle the conversion.

This fixes build failures on 32-bit RISC-V.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/9819)