merge revision(s) 53517,53519,53521,53522,53523,53526,53527:
drop osx and clang because they are often fails and slow * .travis.yml: removed osx code. follow up with r53517 * .travis.yml: removed commented-out code.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@54356 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
merge revision(s) 53517,53519,53521,53522,53523,53526,53527:
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@54356 b2dd03c8-39d4-4d8f-98ff-823fe69b080e