Use RbConfig instead of Config

Author: BanzaiMan

spec/launcher_spec.rb

@@ -156,7 +156,7 @@
   end
 
   # JRUBY-4608
-  if Config::CONFIG['target_os'] =~ /darwin/i
+  if RbConfig::CONFIG['target_os'] =~ /darwin/i
     it "includes file.encoding=UTF-8 on Mac if JAVA_ENCODING is not set" do
       jruby_launcher_args("-e true").should include("-Dfile.encoding=UTF-8")
       with_environment "JAVA_ENCODING" => "MacRoman" do

spec/spec_helper.rb

@@ -9,10 +9,10 @@
 
 module JRubyLauncherHelper
   JRUBY_EXE = ''
-  WINDOWS = Config::CONFIG['target_os'] =~ /mswin/
+  WINDOWS = RbConfig::CONFIG['target_os'] =~ /mswin/
 
   def self.check_executable_built
-    exe = File.expand_path("../../jruby", __FILE__) + Config::CONFIG['EXEEXT']
+    exe = File.expand_path("../../jruby", __FILE__) + RbConfig::CONFIG['EXEEXT']
     unless File.executable?(exe)
       raise "Error: launcher executable not built; type `make' before continuing."
     end