Added bundler as default gems. Revisit [Feature #12733]

* bin/*, lib/bundler/*, lib/bundler.rb, spec/bundler, man/*:
    Merge from latest stable branch of bundler/bundler repository and
    added workaround patches. I will backport them into upstream.
  * common.mk, defs/gmake.mk: Added `test-bundler` task for test suite
    of bundler.
  * tool/sync_default_gems.rb: Added sync task for bundler.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65509 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/bundler/ui/silent.rb

@@ -0,0 +1,69 @@
+# frozen_string_literal: true
+
+module Bundler
+  module UI
+    class Silent
+      attr_writer :shell
+
+      def initialize
+        @warnings = []
+      end
+
+      def add_color(string, color)
+        string
+      end
+
+      def info(message, newline = nil)
+      end
+
+      def confirm(message, newline = nil)
+      end
+
+      def warn(message, newline = nil)
+        @warnings |= [message]
+      end
+
+      def error(message, newline = nil)
+      end
+
+      def debug(message, newline = nil)
+      end
+
+      def debug?
+        false
+      end
+
+      def quiet?
+        false
+      end
+
+      def ask(message)
+      end
+
+      def yes?(msg)
+        raise "Cannot ask yes? with a silent shell"
+      end
+
+      def no?
+        raise "Cannot ask no? with a silent shell"
+      end
+
+      def level=(name)
+      end
+
+      def level(name = nil)
+      end
+
+      def trace(message, newline = nil, force = false)
+      end
+
+      def silence
+        yield
+      end
+
+      def unprinted_warnings
+        @warnings
+      end
+    end
+  end
+end