Log Message:
Update ruby-twitter to 5.16.0.

pkgsrc changes:
- remove unnecesary OVERRIDE_GEMSPEC for ruby-http
- add a new OVERRIDE_GEMSPEC for equalizer-0.0.11
  (briefly tested with net/ruby-tw)

No CHANGELOG.md entry (and no announcement) in upstream.
(one notable change in github is "Update http dependency to ~> 1.0")