examples/var_service: use "exec sleep 5" instead of "{ sleep 5; exit; }"

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

examples/var_service/supplicant_if/run

@@ -9,7 +9,7 @@ if="${PWD##*/dhcp_}"
 
 echo "* Upping iface $if"
 # "or sleep" idiom prevents rapid respawning if iface does not exist
-ip link set dev "$if" up || { sleep 5; exit; }
+ip link set dev "$if" up || exec sleep 5
 
 ##echo "* Powersave disable on $if"
 ##iw dev "$if" set power_save off