Remove use of boost from Logging.hpp

This helps prevent leaking of boost names into Arm NN public headers.

Change-Id: I1605d2ed178965f8e502bc6a4b4ac3e627bbbbed
Signed-off-by: Matthew Bentham <Matthew.Bentham@arm.com>
diff --git a/Android.mk b/Android.mk
index a8f96f5..bfaee44 100644
--- a/Android.mk
+++ b/Android.mk
@@ -90,6 +90,7 @@
         src/armnn/Layer.cpp \
         src/armnn/LayerSupport.cpp \
         src/armnn/LoadedNetwork.cpp \
+        src/armnn/Logging.cpp \
         src/armnn/Network.cpp \
         src/armnn/NetworkUtils.cpp \
         src/armnn/Observable.cpp \