IVGCVSW-5587 Remove Tensorflow requirement from Arm NN TfLite delegate

 * Added support for building the delegate with an external armnn path
 * Replaced potentially troublesome package manager
 * Explicitly set the privacy levels of delegate libraries
 * Fixed some error handling in ExecuteNetwork

Signed-off-by: Finn Williams <Finn.Williams@arm.com>
Change-Id: I2a7abc099796012cbb043c5b319f81778c9f3b56
diff --git a/CMakeLists.txt b/CMakeLists.txt
index cee3c2a..763c010 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -41,10 +41,8 @@
 
 
 if (BUILD_ARMNN_TFLITE_DELEGATE)
-
-    list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/delegate/cmake/Modules)
+    set(ARMNN_SUB_PROJECT ON)
     add_subdirectory(delegate)
-
     add_definitions(-DARMNN_TF_LITE_DELEGATE)
 endif()