Initialize stack allocated memory

Some functions allocated memory on stack without clearing memory and
then send them on wire. This is not an issue, but valgrind reports this
as a problem so it is easy to miss real problem then.

Solution is to clear stack memory.

Signed-off-by: Jan Friesse <jfriesse@redhat.com>
Reviewed-by: Christine Caulfield <ccaulfie@redhat.com>