DO NOT MERGE ANYWHERE - Add libbase to otatools
DO NOT MERGE ANYWHERE - Add libbase to otatools

build_verity_tree uses libbase since b104044.

Change-Id: I6d3406a107ceb6cd58d1a51aa79935209d4c435f

xorware/android_build,xorware/android_build,xorware/android_build,xorware/android_build,xorware/android_build