Add RFC5764 - SRTP key generation during DTLS handshake

Signed-off-by: Johan Pascal <johan.pascal@belledonne-communications.com>
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 48e8855..2ed3ec2 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -1813,6 +1813,17 @@
 #define MBEDTLS_SSL_DTLS_HELLO_VERIFY
 
 /**
+ * \def MBEDTLS_SSL_DTLS_SRTP
+ *
+ * Enable support for DTLS-SRTP, RFC5764
+ *
+ * Requires: MBEDTLS_SSL_PROTO_DTLS
+ *
+ * Comment this to disable support for DTLS-SRTP.
+ */
+#define MBEDTLS_SSL_DTLS_SRTP
+
+/**
  * \def MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE
  *
  * Enable server-side support for clients that reconnect from the same port.