url: fix CURLOPT_DNS_CACHE_TIMEOUT arg value check to allow -1

Prior to this change since f121575 (7.56.1+) CURLOPT_DNS_CACHE_TIMEOUT
erroneously rejected -1 with CURLE_BAD_FUNCTION_ARGUMENT.

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/url.c b/lib/url.c
index c334578ea..2e801e58f 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -722,7 +722,7 @@ CURLcode Curl_setopt(struct Curl_easy *data, CURLoption option,
   switch(option) {
   case CURLOPT_DNS_CACHE_TIMEOUT:
     arg = va_arg(param, long);
-    if(arg < 0)
+    if(arg < -1)
       return CURLE_BAD_FUNCTION_ARGUMENT;
     data->set.dns_cache_timeout = arg;
     break;