* tool/update-deps: Use $(hdrdir) if possible.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48897 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Update dependencies.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48898 b2dd03c8-39d4-4d8f-98ff-823fe69b080e