merge revision(s) 57423:
Fix function name for DBM on extension document. Patch by Yuji Yaginuma, @y-yagi <yuuji.yaginuma@gmail.com> [ci skip][fix GH-1519]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_4@57873 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
merge revision(s) 57423:
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_4@57873 b2dd03c8-39d4-4d8f-98ff-823fe69b080e