retire old rbenv-ruby not used in prod
remove dead mirror
respect RUBY_BUILD_MIRROR_URL and support file://

newer tinderbox does not allow network access in build.
unbreak rbenv-ruby family

- fetch required distfiles before build
- use files in DISTDIR
- create distinfo
Merge pull request #218 from reallyenglish/tomoyukis

unbreak rbenv-ruby family
checkout */hs-* from the master 52b6ecfa0d99b9ed0c118c295ede0a31210baccd

our hs-* ports were too old to fetch
update ports reququired by www/hs-gitit as well.