* tool/mkconfig.rb (RbConfig): prefix SDKROOT to oldincludedir not includedir, the latter is outside the ruby installation. [ruby-core:72496] [Bug #11881] git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53400 b2dd03c8-39d4-4d8f-98ff-823fe69b080e