Bug#1117434: and also cares is missing

[Thomas Braun]

A local development version of cppTango has

$ldd /usr/local/lib/libtango.so | grep ares
        libcares.so.2 => /lib/x86_64-linux-gnu/libcares.so.2
(0x00007fc835602000)
$ldd /usr/local/lib/libtango.so | grep curl
        libopentelemetry_http_client_curl.so =>
/usr/local/lib/libopentelemetry_http_client_curl.so
(0x00007fb7f0271000)
        libcurl-gnutls.so.4 => /lib/x86_64-linux-gnu/libcurl-
gnutls.so.4 (0x00007fb7eedf9000)

so I think also libc-ares-dev [1] is missing as build-dependency.

[1]: https://tracker.debian.org/pkg/c-ares