libcurl-thread.3: also mention threaded-resolver

.\" *                            | (__| |_| |  _ <| |___

.\" *                             \___|\___/|_| \_\_____|

.\" *

.\" * Copyright (C) 2015 - 2016, Daniel Stenberg, <daniel@haxx.se>, et al.

.\" * Copyright (C) 2015 - 2017, Daniel Stenberg, <daniel@haxx.se>, et al.

.\" *

.\" * This software is licensed as described in the file COPYING, which

.\" * you should have received as part of this distribution. The terms

multiple threads you should set the \fICURLOPT_NOSIGNAL(3)\fP option to 1L for

all handles. Everything will or might work fine except that timeouts are not

honored during the DNS lookup - which you can work around by building libcurl

with c-ares support. c-ares is a library that provides asynchronous name

resolves. On some platforms, libcurl simply will not function properly

multi-threaded unless this option is set.

with c-ares or threaded-resolver support. c-ares is a library that provides

asynchronous name resolves. On some platforms, libcurl simply will not

function properly multi-threaded unless the \fICURLOPT_NOSIGNAL(3)\f option is

set.

.IP "Name resolving"

\fBgethostby* functions and other system calls.\fP These functions, provided

by your operating system, must be thread safe. It is very important that