iprule: fix segfault (FS#1875)

iprule: fix segfault (FS#1875)

Fix segfault in generic_interface_cb by checking the
IPRULE_OUT/IPRULE_IN flags before doing the strcmp for the possible
configured out/in interface(s) of the ip rule.
Also don't copy the interface layer3 device as the layer 3 device is
not yet known when IFEV_CREATE event is launched.
The layer3 device will be known when the IFEV_UP event is processed in
rule_out_cb/rule_in_cb.

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>