curl: enable c-ares

This enables the `--dns-servers` option.

Fixes: https://github.com/NixOS/nixpkgs/issues/451543
Signed-off-by: David Wronek <david.wronek@mainlining.org>

pkgs/top-level/all-packages.nix

@@ -2590,6 +2590,7 @@ with pkgs;
       pslSupport = true;
       zstdSupport = true;
       http3Support = true;
+      c-aresSupport = true;
     }
     // lib.optionalAttrs (!stdenv.hostPlatform.isStatic) {
       brotliSupport = true;