base.bbclass: Set umask 022 also for do_unpack task
* when git checkouts files from fetched clone it respects system umask
and creates files with different permissions, if such files are copied
to packages, resulting target images have also different permissions
on them.
* we need reproducible builds across different builders with different
system umask, so set 022 umask
[YOCTO #5590]
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
