docs: use CURLSSLBACKEND_NONE

[ssl] use CURLSSLBACKEND_NONE instead of (curl_sslbackend)-1 in
documentation and examples.

Signed-off-by: Ted Lyngmo <ted@lyncon.se>

Closes #11909

1 files changed, 2 insertions, 2 deletions

diff --git a/docs/examples/sslbackend.c b/docs/examples/sslbackend.c
index 76744730f..fd2b57534 100644
--- a/docs/examples/sslbackend.c
+++ b/docs/examples/sslbackend.c
@@ -49,7 +49,7 @@ int main(int argc, char **argv)
     const curl_ssl_backend **list;
     int i;
 
-    result = curl_global_sslset((curl_sslbackend)-1, NULL, &list);
+    result = curl_global_sslset(CURLSSLBACKEND_NONE, NULL, &list);
     assert(result == CURLSSLSET_UNKNOWN_BACKEND);
 
     for(i = 0; list[i]; i++)
@@ -64,7 +64,7 @@ int main(int argc, char **argv)
     result = curl_global_sslset((curl_sslbackend)id, NULL, NULL);
   }
   else
-    result = curl_global_sslset((curl_sslbackend)-1, name, NULL);
+    result = curl_global_sslset(CURLSSLBACKEND_NONE, name, NULL);
 
   if(result == CURLSSLSET_UNKNOWN_BACKEND) {
     fprintf(stderr, "Unknown SSL backend id: %s\n", name);