To avoid reporting errors for /etc/timestamp is not writeable in a
readonly system.
Reported-by: Niklas Soderlund <niklas.soderlund@external.atlascopco.com>
(From OE-Core rev: 463bef8b055f8305b7aac5045fefe4276b1432ad)
Signed-off-by: Ming Liu <peter.x.liu@external.atlascopco.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>