Configure switch to enable 64-bit time_t?

[Freddie Chopin]

Hello!

Would it be a good idea to have a configure switch which would force
time_t to be 64-bit "long long" instead of 32-bit "long"? Or maybe it
would be a better idea to have "long long" as default now for all
platforms? The problematic moment is 22 years away, but some of my
customers like to be sure that the devices they sell can work until the
"end of days", not just until 2038 (;

Regards,
FCh