Xcode.bad_xcode_select_path? is used only once, so inline it

Library/Homebrew/os/mac/xcode.rb

@@ -14,11 +14,6 @@ module OS
         @folder ||= `xcode-select -print-path 2>/dev/null`.strip
       end
 
-      # Xcode 4.3 tools hang if "/" is set
-      def bad_xcode_select_path?
-        folder == "/"
-      end
-
       def latest_version
         case MacOS.version
         when "10.4"         then "2.5"

Library/brew.rb

@@ -34,7 +34,7 @@ end
 # Check for bad xcode-select before anything else, because `doctor` and
 # many other things will hang
 # Note that this bug was fixed in 10.9
-if OS.mac? && MacOS.version < :mavericks && MacOS::Xcode.bad_xcode_select_path?
+if OS.mac? && MacOS.version < :mavericks && MacOS::Xcode.folder == "/"
   odie <<-EOS.undent
   Your xcode-select path is currently set to '/'.
   This causes the `xcrun` tool to hang, and can render Homebrew unusable.