yaffsfs_CurrentTime() returns the wall clock, and Yaffs writes that value
to the access, modification and change time of every object header. The
RouterBOARD images of ipq40xx/mikrotik therefore differ on every build,
and so does the sysupgrade metadata checksum that follows them.
Add a patch that reads SOURCE_DATE_EPOCH, which the build already exports.
Tested with two images written one second apart. They are identical with
SOURCE_DATE_EPOCH set and differ without it.
Signed-off-by: John Crispin <john@phrozen.org>
John Crispin
ec4768fbed