zoneinfo: don't install version

The commit teaching the build to install tzdata.zi for libcxx also
instals version. It turns out this makes at least one piece of third
party software cry: rubygem-tzinfo expects any file in zoneinfo to be at
least 44 bytes long. Clearly this is a bug in rubygem-tzinfo but since
nothing actually uses version, we may as well not install it ... as we
did previously.

Reported by: delphij
Fixes: 91506dba7f2e zoneinfo: also install tzdata.zi and version
MFC after: 1 day