Missing strftime on BSDs

[Jan Beich]

Target: x86_64-unknown-dragonfly, x86_64-unknown-freebsd, x86_64-unknown-netbsd, x86_64-unknown-openbsd
API: DragonFly, FreeBSD, NetBSD, OpenBSD
Implementation: BSD 4.3 Reno (historic), DragonFly, FreeBSD, NetBSD, OpenBSD
Test case: graf, niri, fish-shell (without bsd workaround).