ipsec.aes_128_gcm: Add stub and tests for correctly deriving hash subkey.
ipsec.aes_128_gcm: Add stub and tests for correctly deriving hash subkey.

dpino/snabb,heryii/snabb,eugeneia/snabb,snabbco/snabb,heryii/snabb,SnabbCo/snabbswitch,mixflowtech/logsensor,SnabbCo/snabbswitch,eugeneia/snabb,alexandergall/snabbswitch,Igalia/snabbswitch,snabbco/snabb,SnabbCo/snabbswitch,alexandergall/snabbswitch,Igalia/snabb,Igalia/snabbswitch,wingo/snabb,dpino/snabbswitch,kbara/snabb,Igalia/snabb,eugeneia/snabbswitch,wingo/snabbswitch,alexandergall/snabbswitch,eugeneia/snabb,Igalia/snabb,kbara/snabb,heryii/snabb,eugeneia/snabbswitch,wingo/snabb,alexandergall/snabbswitch,eugeneia/snabbswitch,kbara/snabb,eugeneia/snabb,mixflowtech/logsensor,Igalia/snabbswitch,dpino/snabbswitch,snabbco/snabb,dpino/snabb,dpino/snabb,kbara/snabb,kbara/snabb,kbara/snabb,dpino/snabbswitch,eugeneia/snabb,snabbco/snabb,mixflowtech/logsensor,mixflowtech/logsensor,mixflowtech/logsensor,wingo/snabbswitch,wingo/snabb,Igalia/snabb,alexandergall/snabbswitch,SnabbCo/snabbswitch,snabbco/snabb,dpino/snabb,Igalia/snabb,wingo/snabb,wingo/snabb,snabbco/snabb,alexandergall/snabbswitch,wingo/snabb,snabbco/snabb,Igalia/snabbswitch,eugeneia/snabb,Igalia/snabb,Igalia/snabbswitch,heryii/snabb,eugeneia/snabb,snabbco/snabb,Igalia/snabb,dpino/snabb,eugeneia/snabb,alexandergall/snabbswitch,heryii/snabb,dpino/snabb,wingo/snabbswitch,eugeneia/snabbswitch,dpino/snabb,dpino/snabbswitch,Igalia/snabb,heryii/snabb,alexandergall/snabbswitch,wingo/snabbswitch