MLCE-64: Updating BuildGuideAndroidNDK.md for Ubuntu 18.04
MLCE-64: Updating BuildGuideAndroidNDK.md for Ubuntu 18.04

Change-Id: Iab9c4952f5478d4805dba56e838f9c33d2b598ee

ARM-software/armnn,ARM-software/armnn,ARM-software/armnn