Ruby

• test/runner.rb: use official repository for coverage tool.
• Makefile.in: ditto.
• common.mk: ditto.
• .gitignore: ignored third party repositories.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@52502 b2dd03c8-39d4-4d8f-98ff-823fe69b080e