Ruby » Ruby master

merge revision(s) 53435: [Backport #11945]

    * ext/stringio/stringio.c (strio_binmode): implement to set encoding

    * test/stringio/test_stringio.rb (test_binmode): new test
      [ruby-core:72699] [Bug #11945]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@54353 b2dd03c8-39d4-4d8f-98ff-823fe69b080e