Define http_listener_impl and http_server_api if CPPREST_FORCE_HTTP_LISTENER_ASIO is defined

Author: garethsb

Release/src/http/listener/http_listener.cpp

@@ -13,7 +13,7 @@
 
 #include "stdafx.h"
 
-#if !defined(_WIN32) || (_WIN32_WINNT >= _WIN32_WINNT_VISTA && !defined(__cplusplus_winrt))
+#if !defined(_WIN32) || (_WIN32_WINNT >= _WIN32_WINNT_VISTA && !defined(__cplusplus_winrt)) || defined(CPPREST_FORCE_HTTP_LISTENER_ASIO)
 
 using namespace web::http::experimental;
 

Release/src/http/listener/http_server_api.cpp

@@ -11,7 +11,7 @@
 
 #include "stdafx.h"
 
-#if !defined(_WIN32) || (_WIN32_WINNT >= _WIN32_WINNT_VISTA && !defined(__cplusplus_winrt))
+#if !defined(_WIN32) || (_WIN32_WINNT >= _WIN32_WINNT_VISTA && !defined(__cplusplus_winrt)) || defined(CPPREST_FORCE_HTTP_LISTENER_ASIO)
 #include "http_server_impl.h"
 
 using namespace web;