kernel/reproducibility: kernel modules need SOURCE_DATE_EPOCH export
If CONFIG_IKHEADERS is set to =m, then reproducibility issues creep
into the modules build, since the variables we are setting for the
main kernel build are not present.
Since the source code must be available for a possibly git query
on the timestamp, there didn't seem to be an easy way to move the
environment variable setting to a common routine. As such, we
duplicate the block of code that exports the required variables for
reproducible builds. There is a maintenance risk to this, but any
issues should be easy enough to catch.
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
