openssl wrapper: introduce SSL_get0_param

This adds the standard OpenSSL api to get a pointer to the SSL struct's
X509_VERIFY_PARAM.  We need this for the OpenSSL api to set the peer
hostname introduced in the next patch.

Part of https://github.com/espressif/esp-idf/pull/980

components/openssl/include/openssl/ssl.h

@@ -1523,6 +1523,15 @@ long SSL_get_timeout(const SSL *ssl);
  */
 int SSL_get_verify_mode(const SSL *ssl);
 
+/**
+ * @brief get SSL verify parameters
+ *
+ * @param ssl - SSL point
+ *
+ * @return verify parameters
+ */
+X509_VERIFY_PARAM *SSL_get0_param(SSL *ssl);
+
 /**
  * @brief get SSL write only IO handle
  *

components/openssl/library/ssl_x509.c

@@ -117,6 +117,15 @@ failed1:
     return NULL;
 }
 
+/**
+ * @brief return SSL X509 verify parameters
+ */
+
+X509_VERIFY_PARAM *SSL_get0_param(SSL *ssl)
+{
+    return &ssl->param;
+}
+
 /**
  * @brief set SSL context client CA certification
  */