Improve backwards compat with 1.0.2 for ECDHParameters

In 1.0.2 you could configure automatic ecdh params by using the
ECDHParameters config directive and setting it to the value
"+Automatic" or just "Automatic". This is no longer required in 1.1.0+
but we still recognise the "+Automatic" keyword for backwards compatibility.
However we did not recognise just "Automatic" without the leading "+" which
is equally valid. This commit fixes that omission.

Fixes #4113
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6035)

doc/man3/SSL_CONF_cmd.pod

@@ -597,10 +597,6 @@ Set supported curves to P-256, P-384:
 
  SSL_CONF_cmd(ctx, "Curves", "P-256:P-384");
 
-Set automatic support for any elliptic curve for key exchange:
-
- SSL_CONF_cmd(ctx, "ECDHParameters", "Automatic");
-
 =head1 RETURN VALUES
 
 SSL_CONF_cmd() returns 1 if the value of B<cmd> is recognised and B<value> is

ssl/ssl_conf.c

@@ -229,8 +229,9 @@ static int cmd_ECDHParameters(SSL_CONF_CTX *cctx, const char *value)
     int nid;
 
     /* Ignore values supported by 1.0.2 for the automatic selection */
-    if ((cctx->flags & SSL_CONF_FLAG_FILE) &&
-        strcasecmp(value, "+automatic") == 0)
+    if ((cctx->flags & SSL_CONF_FLAG_FILE)
+            && (strcasecmp(value, "+automatic") == 0
+                || strcasecmp(value, "automatic") == 0))
         return 1;
     if ((cctx->flags & SSL_CONF_FLAG_CMDLINE) &&
         strcmp(value, "auto") == 0)