fff-config: Set panic on OOM

The OOM killer does not make much sense on a router, because regardless
of which process is killed, most of the time some essential core
functionality is affected.

Set the panic on OOM sysctl, so every OOM leads to a kernel panic and
results in a reboot of the router, which restores a clean state.

Fixes: #131

Signed-off-by: Fabian Bläse <fabian@blaese.de>
Reviewed-by: Johannes Kimmel <fff@bareminimum.eu>

src/packages/fff/fff-config/files/etc/sysctl.d/20-oom-panic.conf

@@ -0,0 +1 @@
+vm.panic_on_oom=1