Add dependencies for experimental TLS 1.3 features in check_config.h

Signed-off-by: Hanno Becker <hanno.becker@arm.com>
diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h
index fa3caa7..4111b37 100644
--- a/include/mbedtls/check_config.h
+++ b/include/mbedtls/check_config.h
@@ -619,6 +619,11 @@
 #error "MBEDTLS_SSL_PROTO_TLS1_2 defined, but not all prerequisites"
 #endif
 
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL) && ( !defined(MBEDTLS_HKDF_C) \
+    !defined(MBEDTLS_SHA256_C) && !defined(MBEDTLS_SHA512_C) )
+#error "MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL defined, but not all prerequisites"
+#endif
+
 #if (defined(MBEDTLS_SSL_PROTO_SSL3) || defined(MBEDTLS_SSL_PROTO_TLS1) ||  \
      defined(MBEDTLS_SSL_PROTO_TLS1_1) || defined(MBEDTLS_SSL_PROTO_TLS1_2)) && \
     !(defined(MBEDTLS_KEY_EXCHANGE_RSA_ENABLED) ||                          \