IVGCVSW-2022 : fix for backend cmake files to respect BUILD_UNIT_TESTS variable

Change-Id: I8d34419742152edd50f1ec438e32d3ccc4f38351
diff --git a/src/backends/cl/CMakeLists.txt b/src/backends/cl/CMakeLists.txt
index 5704e0e..d38fb68 100644
--- a/src/backends/cl/CMakeLists.txt
+++ b/src/backends/cl/CMakeLists.txt
@@ -21,7 +21,10 @@
     )
 
     add_subdirectory(workloads)
-    add_subdirectory(test)
+
+    if(BUILD_UNIT_TESTS)
+        add_subdirectory(test)
+    endif()
 endif()
 
 add_library(armnnClBackend OBJECT ${armnnClBackend_sources})