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/cmake/GlobalConfig.cmake b/cmake/GlobalConfig.cmake
index 191cd9d..51a7efd 100644
--- a/cmake/GlobalConfig.cmake
+++ b/cmake/GlobalConfig.cmake
@@ -302,6 +302,11 @@
     add_definitions(-DARMNNREF_ENABLED)
 endif()
 
+# ArmNN dynamic backend
+if(DYNAMIC_BACKEND_PATHS)
+    add_definitions(-DARMNN_DYNAMIC_BACKEND_ENABLED)
+endif()
+
 # Streamline annotate
 if(PROFILING_BACKEND_STREAMLINE)
     include_directories("${GATOR_ROOT}/annotate")