Expose set_groups/set_curves functions

This allows pyOpenSSL to restrict the groups allowed to be used. E.g.
for restricting the groups to post-quantum hybrid groups
(e.g. X25519MLKEM768) to always ensure that post-quantum cryptography is
used.

This commit uses the set_curves instead of the set_groups variant since
that naming is available on all OpenSSL versions and forks.

Signed-off-by: Arne Schwabe <arne@rfc2549.org>

Author: schwabe

src/_cffi_src/openssl/ssl.py

@@ -346,6 +346,13 @@
 
 const char *SSL_get0_group_name(SSL *);
 
+/* both functions are have int return type according to the man page but
+ * long in its implementation. Newer versions also have the set1_groups
+ * function but the curves variants are availalbe on all forks and OpenSSL
+ * variants */
+long SSL_CTX_set1_curves_list(SSL_CTX *, char *);
+long SSL_set1_curves_list(SSL *, char *);
+
 void SSL_set_tlsext_host_name(SSL *, char *);
 void SSL_CTX_set_tlsext_servername_callback(
     SSL_CTX *,