y2038: Add __USE_TIME_BITS64 support for socket-constants.h

y2038: Add __USE_TIME_BITS64 support for socket-constants.h

It is only used for !__USE_MISC, the default way uses the kernel
headers.  The patch also adds the SO_TIMESTAMP, SO_TIMESTAMPNS, and
SO_TIMESTAMPING which uses new values for 64-bit time_t kernel
interfaces.

The __USE_TIME_BITS64 is not defined internally yet, although the
internal header is used when building the 64-bit stat implementations.

Reviewed-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>