Use correct value for the basic_resolver_results::end() iterator.

asio/include/asio/ip/basic_resolver_results.hpp

diff --git a/asio/include/asio/ip/basic_resolver_results.hpp b/asio/include/asio/ip/basic_resolver_results.hpp
index 001fad2..bb4601a 100644
--- a/asio/include/asio/ip/basic_resolver_results.hpp
+++ b/asio/include/asio/ip/basic_resolver_results.hpp
@@ -258,9 +258,7 @@
   /// Obtain an end iterator for the results range.
   const_iterator end() const
   {
-    basic_resolver_results tmp(*this);
-    tmp.index_ = size();
-    return tmp;
+    return const_iterator();
   }
 
   /// Obtain a begin iterator for the results range.