opkg-utils: Fix reproducibility issues in opkg-build
There is a sorting problem with opkg-build where the ipk generated is depending
upon the order of files on disk. The reason is the --sort option to tar only
influences the orders of files tar reads, not those passed by the -T option.
Add in a sort call to resolve this issue. To ensure consistent sorting we
also need to force to a specific locale (C) else the results are still not
deterministic.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
