Refuse to build the library if deprecated features are excluded

Mbed Crypto is no longer being updated, so using it is deprecated.

Don't test with MBEDTLS_DEPRECATED_REMOVED anymore since the library
deliberately no longer builds when it's enabled.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h
index df35a16..ae7469e 100644
--- a/include/mbedtls/check_config.h
+++ b/include/mbedtls/check_config.h
@@ -30,6 +30,9 @@
 #ifndef MBEDTLS_CHECK_CONFIG_H
 #define MBEDTLS_CHECK_CONFIG_H
 
+#if defined(MBEDTLS_DEPRECATED_REMOVED)
+#error "Mbed Crypto is no longer being updated. Please use Mbed TLS instead. See README.md."
+#endif
 #if defined(MBEDTLS_DEPRECATED_WARNING)
 #warning "Mbed Crypto is no longer being updated. Please use Mbed TLS instead. See README.md."
 #endif