configure.in: CoreFoundation framework option

* configure.in (XLDFLAGS, LIBRUBYARG_STATIC): CoreFoundation framework
  option is now needed always, regardless enable-shared.
  [ruby-core:56467] [Bug #8759]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42472 b2dd03c8-39d4-4d8f-98ff-823fe69b080e