Update timezone to C99

Update timezone to C99

This reverts changes done in PostgreSQL over the upstream code to
avoid relying on C99 <stdint.h> and <inttypes.h>.

In passing, there were a few other minor and cosmetic changes that I
left in to improve alignment with upstream, including some C11 feature
use (_Noreturn).

Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/9ad2749f-77ab-4ecb-a321-1ca915480b05%40eisentraut.org