sstate: Set umask to 002 before packaging runs

sstate: Set umask to 002 before packaging runs

Otherwise we might end up creating directories under sstate-cache with whatever
random umask has been selected for the task that we're trying to package.  This
would be a bad thing since it might result in losing group write access for
newly created dirs, and/or losing group read access for the sstate files
themselves.

(From OE-Core rev: d8c4f442c41bf3ac5e064630657cd3fa1b5c43b1)

Signed-off-by: Phil Blundell <philb@gnu.org>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>