avoid races with application upon connection upgrade: update state/response before calling MHD_response_execute_upgrade_
avoid races with application upon connection upgrade: update state/response before calling MHD_response_execute_upgrade_

ghaderer/libmicrohttpd,maru/libmicrohttpd-http2,ghaderer/libmicrohttpd,ghaderer/libmicrohttpd,maru/libmicrohttpd-http2,maru/libmicrohttpd-http2