Add a script to put in a rootfs from one image into another.

Also add an option to prevent sign_official_build from attempting to re-sign the firmware.

This is needed because we want both the SSD and RECOVERY images to have the same rootfs for delta updates to work correctly.

BUG=chromium-os:7242
TEST=manually verified that rootfs gets replaced correctly (by verifying the rootfs hash).

Change-Id: I2ca4f2bef938ca14301fed6a0b16c1a7dc2ba6d9

Review URL: http://codereview.chromium.org/3529007
2 files changed