build scripts for tc0

After cloning build-scripts at the root of the android tree,
call the script from the root of android source tree
with the following options:

-d, --distro  distro version, values supported [android-nano, android-swr]
-a, --avb     [OPTIONAL] avb boot, values supported [true, false], DEFAULT: false

The add_uboot_header.sh and create_android_image.sh are helper
scripts to create the required images.

Change-Id: I500f62a8e0afdc690458f8bd9fc67a0290508034
Signed-off-by: Usama Arif <usama.arif@arm.com>