build: link bundled libcurl with c-ares

libcurl has a built-in threaded resolver used for asynchronous DNS
requests, however, when DNS server is slow to respond, the request still
hangs tarantool until it is finished. The reason is that curl calls
thread_join on the resolving thread internally upon timeout, making the
calling thread hang until resolution has ended.
Use c-ares as an asynchronous resolver instead to eliminate the problem.

Closes #4591