Fix curl signal handling conflict

- https_client.c: Set CURLOPT_NOSIGNAL to 1 to disable curl's internal
  signal handling and prevent interference with libev's signal watchers.

Author: aarond10

src/https_client.c

@@ -309,7 +309,7 @@ static void https_fetch_ctx_init(https_client_t *client,
   ASSERT_CURL_EASY_SETOPT(ctx, CURLOPT_PIPEWAIT, (long)(client->opt->use_http_version > 1));
   ASSERT_CURL_EASY_SETOPT(ctx, CURLOPT_USERAGENT, "https_dns_proxy/0.4");
   ASSERT_CURL_EASY_SETOPT(ctx, CURLOPT_FOLLOWLOCATION, 0L);
-  ASSERT_CURL_EASY_SETOPT(ctx, CURLOPT_NOSIGNAL, 0L);
+  ASSERT_CURL_EASY_SETOPT(ctx, CURLOPT_NOSIGNAL, 1L);  // Disable curl's signal handling to avoid conflicts with libev
   ASSERT_CURL_EASY_SETOPT(ctx, CURLOPT_TIMEOUT, client->connections > 0 ? 5L : 10L /* seconds */);
   // We know Google supports this, so force it.
   ASSERT_CURL_EASY_SETOPT(ctx, CURLOPT_SSLVERSION, (long)CURL_SSLVERSION_TLSv1_2);