IVGCVSW-4212 Example of standalone dynamic reference backend

 * Add example to build dynamic reference backend
 * Add functions to clear dynamic backends
 * Fix the error when dynamic backend is not deregistered
 * Add DYARMNN_DYNAMIC_BACKEND_ENABLED to check disable empty
   dynamic backend when dynamic backend is enabled

Signed-off-by: Narumol Prangnawarat <narumol.prangnawarat@arm.com>
Change-Id: I1ef3a3f10ed6ca5ec18d0af04b007fc3bc71a3cb
diff --git a/src/dynamic/reference/RefDynamicBackend.hpp b/src/dynamic/reference/RefDynamicBackend.hpp
new file mode 100644
index 0000000..bc680a1
--- /dev/null
+++ b/src/dynamic/reference/RefDynamicBackend.hpp
@@ -0,0 +1,15 @@
+//
+// Copyright © 2019 Arm Ltd. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+
+#pragma once
+
+#include <cstdint>
+
+extern "C"
+{
+const char* GetBackendId();
+void GetVersion(uint32_t* outMajor, uint32_t* outMinor);
+void* BackendFactory();
+}