timedate: remove daylight saving time handling and tzfile parser

timedate: remove daylight saving time handling and tzfile parser

We planned to support (the conceptually broken) daylight saving
time/local time features in the kernel, SCSI, networking, FAT
filesystem, but it turned out to be a race we cannot win and do
not want to get involved. Systemd should not fiddle with daylight
saving time or parse timezone information itself.

Leave everything to glibc or tools like date(1) and do not make any
promises or raise expectations that systemd should handle anything
like this.