Add in ext4 support for ASEC containers

Now forward locked applications will be in ASEC containers both internal
to the system and externally.

This change adds support for putting applications in ext4-based ASECs.

Change-Id: I8d6765b72dd2606e429c067b47a2dbcaa8bef37d
diff --git a/Android.mk b/Android.mk
index 54abb23..e4256ae 100644
--- a/Android.mk
+++ b/Android.mk
@@ -10,6 +10,7 @@
 	DirectVolume.cpp \
 	logwrapper.c \
 	Process.cpp \
+	Ext4.cpp \
 	Fat.cpp \
 	Loop.cpp \
 	Devmapper.cpp \