Fix the MAX_CURVELIST definition

The MAX_CURVELIST macro defines the total number of in-built SSL/TLS curves
that we support. However it has not been updated as new curves are added.

Fixes #5232

Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
(Merged from https://github.com/openssl/openssl/pull/6065)

ssl/t1_lib.c

diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index b777b3a..6f4923d 100644
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -366,7 +366,7 @@
     return 1;
 }
 
-# define MAX_CURVELIST   28
+# define MAX_CURVELIST   OSSL_NELEM(nid_list)
 
 typedef struct {
     size_t nidcnt;