BUG/MINOR: lua: fix setting netfilter mark

In the REORG of commit 1a18b5414 ("REORG: connection: centralize the
conn_set_{tos,mark,quickack} functions") a bug was introduced by
calling conn_set_tos instead of conn_set_mark.

This was reported in issue #212

This should be backported to 1.9 and 2.0.
1 file changed