asterisk: Implement support to handle 2nd REGISTER through ipsec

This patch implements the necessary infra to set up ipsec tunnel towards
the asterisk IMS client, and receive the 2nd REGISTER through the ipsec
tun plus answer it acking the registration successfully.

Change-Id: Ic042422788ee406f5b71ca3878bc5617e5455579
diff --git a/asterisk/regen_makefile.sh b/asterisk/regen_makefile.sh
index 5d5538e..8f7eae9 100755
--- a/asterisk/regen_makefile.sh
+++ b/asterisk/regen_makefile.sh
@@ -5,6 +5,7 @@
 FILES="
 	*.c
 	*.ttcn
+	PIPEasp_PT.cc
 	IPL4asp_PT.cc
 	IPL4asp_discovery.cc
 	Native_FunctionDefs.cc
@@ -20,3 +21,6 @@
 "
 
 ../regen-makefile.sh -e $NAME $FILES
+
+# required for forkpty(3) used by PIPEasp
+sed -i -e '/^LINUX_LIBS/ s/$/ -lutil/' Makefile