eap-aka-3gpp: Add plugin that implements 3GPP MILENAGE algorithm in software

This is similar to the eap-aka-3gpp2 plugin. K (optionally concatenated
with OPc) may be configured as binary EAP secret in ipsec.secrets or
swanctl.conf.

Based on a patch by Thomas Strangert.

Fixes #2326.

conf/Makefile.am

@@ -39,7 +39,8 @@ plugins = \
 	plugins/dnscert.opt \
 	plugins/duplicheck.opt \
 	plugins/eap-aka.opt \
-	plugins/eap-aka-3ggp2.opt \
+	plugins/eap-aka-3gpp.opt \
+	plugins/eap-aka-3gpp2.opt \
 	plugins/eap-dynamic.opt \
 	plugins/eap-gtc.opt \
 	plugins/eap-peap.opt \