Move xctoolchain_path to Xcode module, where it belongs

Library/Homebrew/extend/ENV/std.rb

@@ -71,9 +71,7 @@ module Stdenv
     macosxsdk MacOS.version
 
     if MacOS::Xcode.without_clt?
-      # Some tools (clang, etc.) are in the xctoolchain dir of Xcode
-      append_path 'PATH', "#{MacOS.xctoolchain_path}/usr/bin" if MacOS.xctoolchain_path
-      # Others are now at /Applications/Xcode.app/Contents/Developer/usr/bin
+      append_path "PATH", "#{MacOS::Xcode.toolchain_path}/usr/bin"
       append_path 'PATH', MacOS.dev_tools_path
     end
   end

Library/Homebrew/extend/ENV/super.rb

@@ -117,7 +117,7 @@ module Superenv
     paths = [Superenv.bin]
     if MacOS::Xcode.without_clt?
       paths << "#{MacOS::Xcode.prefix}/usr/bin"
-      paths << "#{MacOS::Xcode.prefix}/Toolchains/XcodeDefault.xctoolchain/usr/bin"
+      paths << "#{MacOS::Xcode.toolchain_path}/usr/bin"
     end
     paths += deps.map{|dep| "#{HOMEBREW_PREFIX}/opt/#{dep}/bin" }
     paths << MacOS::X11.bin if x11?

Library/Homebrew/os/mac.rb

@@ -56,16 +56,6 @@ module OS
       %w{cc make}.all? { |tool| File.executable? "#{prefix}/usr/bin/#{tool}" }
     end
 
-    def xctoolchain_path
-      # As of Xcode 4.3, some tools are located in the "xctoolchain" directory
-      @xctoolchain_path ||= begin
-        path = Pathname.new("#{Xcode.prefix}/Toolchains/XcodeDefault.xctoolchain")
-        # If only the CLT are installed, all tools will be under dev_tools_path,
-        # this path won't exist, and xctoolchain_path will be nil.
-        path if path.exist?
-      end
-    end
-
     def sdk_path(v = version)
       (@sdk_path ||= {}).fetch(v.to_s) do |key|
         opts = []

Library/Homebrew/os/mac/xcode.rb

@@ -61,6 +61,10 @@ module OS
         end
       end
 
+      def toolchain_path
+        Pathname.new("#{prefix}/Toolchains/XcodeDefault.xctoolchain") if installed? && version >= "4.3"
+      end
+
       # Ask Spotlight where Xcode is. If the user didn't install the
       # helper tools and installed Xcode in a non-conventional place, this
       # is our only option. See: http://superuser.com/questions/390757