expr: reject: Do not print unset values in xml

It changes the parse and the snprint functions to omit unset values.

If we used this rule:
nft add rule ip test output reject

It gets this xml file:
[...]
<expr type="reject">
	<type>0</type>
	<code>0</code>
</expr>
</rule></nftables>

Now, That rule creates this xml file without null values:

[...]
<expr type="reject">
</expr>
</rule></nftables>

Signed-off-by: Ana Rey <anarey@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

0 files changed, 0 insertions, 0 deletions