Add a SSL_get_key_update_type() function

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2609)
diff --git a/include/openssl/ssl.h b/include/openssl/ssl.h
index ba98a9f..4456de1 100644
--- a/include/openssl/ssl.h
+++ b/include/openssl/ssl.h
@@ -1663,6 +1663,7 @@
 
 __owur int SSL_do_handshake(SSL *s);
 int SSL_key_update(SSL *s, SSL_KEY_UPDATE updatetype);
+SSL_KEY_UPDATE SSL_get_key_update_type(SSL *s);
 int SSL_renegotiate(SSL *s);
 int SSL_renegotiate_abbreviated(SSL *s);
 __owur int SSL_renegotiate_pending(SSL *s);
diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c
index 0ca04bd..927d70a 100644
--- a/ssl/ssl_lib.c
+++ b/ssl/ssl_lib.c
@@ -1743,6 +1743,11 @@
     return 1;
 }
 
+SSL_KEY_UPDATE SSL_get_key_update_type(SSL *s)
+{
+    return s->key_update;
+}
+
 int SSL_renegotiate(SSL *s)
 {
     if (SSL_IS_TLS13(s)) {
diff --git a/util/libssl.num b/util/libssl.num
index d137c93..32b5f76 100644
--- a/util/libssl.num
+++ b/util/libssl.num
@@ -414,3 +414,4 @@
 SSL_CTX_get_keylog_callback             415	1_1_1	EXIST::FUNCTION:
 SSL_get_peer_signature_type_nid         416	1_1_1	EXIST::FUNCTION:
 SSL_key_update                          417	1_1_1	EXIST::FUNCTION:
+SSL_get_key_update_type                 418	1_1_1	EXIST::FUNCTION: