attempt to fix a threading issue on OS X: close() in MHD_stop_daemon will get stuck if someone's in accept(), but select() in MHD_select may get stuck if the socket isn't already closed on shutdown.
attempt to fix a threading issue on OS X: close() in MHD_stop_daemon will get
stuck if someone's in accept(), but select() in MHD_select may get stuck if
the socket isn't already closed on shutdown.

slackner/libmicrohttpd,slackner/libmicrohttpd,pmq20/libmicrohttpd,pmq20/libmicrohttpd,pmq20/libmicrohttpd,slackner/libmicrohttpd