otasigcheck and backuptools from CM

Change-Id: I1b582d57ed58176db83ec046e68884cd9e4a1b6a

Add otasigcheck.sh from cm

Change-Id: I930b06ccd1d8fc2b10bdb5e98418efb05ca28e71

Conflicts:
	config/common.mk
	prebuilt/common/bin/backuptool.functions
	prebuilt/common/bin/backuptool.sh