Import CSV 3.0.8

This includes performance improvements and backward incompatibility
fixes.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@67560 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/csv/delete_suffix.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+# This provides String#delete_suffix? for Ruby 2.4.
+unless String.method_defined?(:delete_suffix)
+  class CSV
+    module DeleteSuffix
+      refine String do
+        def delete_suffix(suffix)
+          if end_with?(suffix)
+            self[0..(-(suffix.size + 1))]
+          else
+            self
+          end
+        end
+      end
+    end
+  end
+end