[libmicrohttpd] External logging

[Sreejith.D]

Hi MHD team/Christian,

I implemented MHD in a windows application via MSYS. To detect some 
intermittent connection-break issues, I implemented external logging. It looks 
straightforward and that is why I doubt if it is the right way to do, too... 
messages are enabled (not compiled with -disable-messages) and I also use 
MHD_USE_DEBUG.

FILE* MHD_logger = NULL; //somewhere in the code

void MHD_external_logger(void * arg, const char * fmt, va_list ap)
{

       if (arg != NULL)
       {
              FILE* _fptr = *((FILE**)(arg));
              vfprintf_s(_fptr, fmt, ap);
       }
}

//...
//
m_pMhd = MHD_start_daemon(flags | MHD_USE_DEBUG, gblusport,
                             //NULL,NULL,
                             AcceptPolicyCallback, this,
                             AccessHandlerCallback, this,
                             MHD_OPTION_CONNECTION_TIMEOUT, (unsigned int)120,
                             MHD_OPTION_SOCK_ADDR, &addr,
                             MHD_OPTION_HTTPS_MEM_KEY, key_file_pem.c_str(),
                             MHD_OPTION_HTTPS_MEM_CERT, cert_file_pem.c_str(),
                             MHD_OPTION_EXTERNAL_LOGGER, MHD_external_logger, 
(void*)MHD_logger,
                             MHD_OPTION_ARRAY, &ops[0],
                             MHD_OPTION_END);


-Sreejith.