Stop complaining about deprecated OpenSSL functions

[Rtoax]

 sshbuf-getput-crypto.c: In function ‘sshbuf_get_eckey’:
 sshbuf-getput-crypto.c:97:9: warning: ‘EC_KEY_get0_group’ is deprecated: Since OpenSSL 3.0 [-Wdeprecated-declarations]
    97 |         EC_POINT *pt = EC_POINT_new(EC_KEY_get0_group(v));
       |         ^~~~~~~~
 In file included from sshbuf-getput-crypto.c:29:
 /usr/include/openssl/ec.h:1032:39: note: declared here
  1032 | OSSL_DEPRECATEDIN_3_0 const EC_GROUP *EC_KEY_get0_group(const EC_KEY *key);
       |                                       ^~~~~~~~~~~~~~~~~

Ref: torvalds/linux@6bfb56e

[martelletto]

Instead of a pragma that suppresses the warning, would it make sense to go with something along the lines of:

diff --git a/configure.ac b/configure.ac
index e7459ee1a..dcf108fa9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2801,7 +2801,9 @@ if test "x$openssl" = "xyes" ; then
                                ;;
                        101*)   ;; # 1.1.x
                        200*)   ;; # LibreSSL
-                       300*)   ;; # OpenSSL 3
+                       300*)
+                               CPPFLAGS="$CPPFLAGS -DOPENSSL_API_COMPAT=0x10100000L"
+                               ;;
                        301*)   ;; # OpenSSL development branch.
                        *)
                                AC_MSG_ERROR([Unknown/unsupported OpenSSL version ("$ssl_library_ver")])

Ref: https://www.openssl.org/docs/manmaster/man7/OPENSSL_API_COMPAT.html

[djmdjm]

Thanks @martelletto - similar patch applied in f51423b