[PATCH 1/2] setup: update to use RbConfig

[James Rowe]

`Config` was removed years ago¹, and is not supported in any Ruby release
that dtas supports.

1. https://bugs.ruby-lang.org/issues/6809
---
 setup.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/setup.rb b/setup.rb
index 9f0c826..65380f4 100644
--- a/setup.rb
+++ b/setup.rb
@@ -785,7 +785,7 @@ def ToplevelInstaller.load_rbconfig
     else
       require 'rbconfig'
     end
-    ::Config::CONFIG
+    ::RbConfig::CONFIG
   end
 
   def initialize(ardir_root, config)
-- 
2.20.1