Make strand destruction a no-op, to allow strand objects to be destroyed
after their associated io_service has been destroyed.

asio/include/asio/detail/impl/strand_service.hpp

diff --git a/asio/include/asio/detail/impl/strand_service.hpp b/asio/include/asio/detail/impl/strand_service.hpp
index 85485f0..3b7ee23 100644
--- a/asio/include/asio/detail/impl/strand_service.hpp
+++ b/asio/include/asio/detail/impl/strand_service.hpp
@@ -49,11 +49,6 @@
   }
 };
 
-inline void strand_service::destroy(strand_service::implementation_type& impl)
-{
-  impl = 0;
-}
-
 template <typename Handler>
 void strand_service::dispatch(strand_service::implementation_type& impl,
     Handler handler)

asio/include/asio/detail/strand_service.hpp

diff --git a/asio/include/asio/detail/strand_service.hpp b/asio/include/asio/detail/strand_service.hpp
index d2fd6e6..53b334c 100644
--- a/asio/include/asio/detail/strand_service.hpp
+++ b/asio/include/asio/detail/strand_service.hpp
@@ -83,9 +83,6 @@
   // Construct a new strand implementation.
   ASIO_DECL void construct(implementation_type& impl);
 
-  // Destroy a strand implementation.
-  void destroy(implementation_type& impl);
-
   // Request the io_service to invoke the given handler.
   template <typename Handler>
   void dispatch(implementation_type& impl, Handler handler);

asio/include/asio/strand.hpp

diff --git a/asio/include/asio/strand.hpp b/asio/include/asio/strand.hpp
index 92f6ccc..8324b14 100644
--- a/asio/include/asio/strand.hpp
+++ b/asio/include/asio/strand.hpp
@@ -104,7 +104,6 @@
    */
   ~strand()
   {
-    service_.destroy(impl_);
   }
 
   /// Get the io_service associated with the strand.