main/tig: fix printing of time_t values on 32 bit arches

See: https://github.com/jonas/tig/issues/1084
7 jobs for !18255 with tig-time_t in 2 minutes and 30 seconds
detached
Status Job ID Name Coverage
  Lint
passed #321946
docker-alpine x86_64
lint

00:00:19

 
  Build
passed #321951
docker-alpine ci-build aarch64
build-aarch64

00:00:27

passed #321952
docker-alpine ci-build armv7
build-armv7

00:00:33

passed #321950
docker-alpine ci-build ppc64le
build-ppc64le

00:00:50

passed #321949
docker-alpine ci-build s390x
build-s390x

00:00:45

passed #321948
docker-alpine ci-build x86
build-x86

00:00:20

passed #321947
docker-alpine ci-build x86_64
build-x86_64

00:00:16