Fix DTLS_SECURE_RENEGOTIATION configuration.

Add missing DTLS_SECURE_RENEGOTIATION to default DEFINITIONS in order to
add the value to the properties file.

Signed-off-by: Achim Kraus <achim.kraus@cloudcoap.net>

scandium-core/src/main/java/org/eclipse/californium/scandium/config/DtlsConfig.java

@@ -1131,6 +1131,7 @@ public void applyDefinitions(Configuration config) {
 			config.set(DTLS_READ_WRITE_LOCK_CONNECTION_STORE, true);
 			config.set(DTLS_MAC_ERROR_FILTER_QUIET_TIME, 0, TimeUnit.SECONDS);
 			config.set(DTLS_MAC_ERROR_FILTER_THRESHOLD, 0);
+			config.set(DTLS_SECURE_RENEGOTIATION, DEFAULT_SECURE_RENEGOTIATION);
 			config.set(DTLS_SUPPORT_KEY_MATERIAL_EXPORT, false);
 		}
 	};