Switched out implementation of http_exception message to reuse windows_category from asyncrt_utils

Author: ras0219-msft

Release/src/http/client/http_win7.cpp

@@ -128,20 +128,8 @@ static std::string build_callback_error_msg(_In_ WINHTTP_ASYNC_RESULT *error_res
         error_msg << "Unknown WinHTTP Function";
         break;
     }
-    error_msg << ": " << error_result->dwError << ": ";
-    std::array<char, 256> buf = { 0 };
-
-    auto hr = ::FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM,
-                              NULL,
-                              error_result->dwError,
-                              MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
-                              buf.data(),
-                              buf.size() - 1,
-                              NULL);
-    if (hr == 0)
-        error_msg << buf.data();
-    else
-        error_msg << "?";
+    error_msg << ": " << error_result->dwError << ": "
+        << utility::details::windows_category().message(error_result->dwError);
     return error_msg.str();
 }