Do not close inherited file descriptors in compiler wrapper

Library/ENV/4.3/cc

@@ -335,5 +335,6 @@ if __FILE__ == $PROGRAM_NAME
   LOGGER.puts "superenv executed: #{tool} #{args.join(" ")}"
   LOGGER.log!
 
+  args << { :close_others => false } if RUBY_VERSION >= "2.0"
   exec "xcrun", tool, *args
 end