Add thin abstraction layer for processes and filesystem

This is used instead of some hardcoded Unix calls and means this code
now works on Windows

(This is a rework of a previous patch which used boost, now that I have
been informed that we are trying to move towards removing boost).

Change-Id: Ib0d11055279bbd7b710f086e9890369e3ecbfe9a
Signed-off-by: Robert Hughes <robert.hughes@arm.com>
diff --git a/src/armnnUtils/Processes.hpp b/src/armnnUtils/Processes.hpp
new file mode 100644
index 0000000..0f1d955
--- /dev/null
+++ b/src/armnnUtils/Processes.hpp
@@ -0,0 +1,16 @@
+//
+// Copyright © 2020 Arm Ltd. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+
+#pragma once
+
+namespace armnnUtils
+{
+namespace Processes
+{
+
+int GetCurrentId();
+
+}
+}