Fix accept error handling in http_server_async example

close #2319

CHANGELOG.md

@@ -1,5 +1,6 @@
 Version XXX:
 
+* Fix accept error handling in http_server_async example.
 * Move library-specific docca configuration to Beast.
 * Remove dependency on RTTI in `test::stream`.
 

example/http/server/async-ssl/http_server_async_ssl.cpp

@@ -500,6 +500,7 @@ private:
         if(ec)
         {
             fail(ec, "accept");
+            return; // To avoid infinite loop
         }
         else
         {

example/http/server/async/http_server_async.cpp

@@ -434,6 +434,7 @@ private:
         if(ec)
         {
             fail(ec, "accept");
+            return; // To avoid infinite loop
         }
         else
         {