Ruby

• ext/tk/extconf.rb, ext/tk/tcltklib.c, ext/tk/tkutil/tkutil.c: Do
  not test ruby/ruby.h, which makes OS X's gcc pick the wrong
  header file from Ruby.framework.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@18076 b2dd03c8-39d4-4d8f-98ff-823fe69b080e