vold: Add encrypted ASEC support via devmapper

- Supports up to 4096 containers
- Keys are now implemented - specifying a key of 'none' means no encryption.
  Otherwise, the key must be a string of 32 characters

Signed-off-by: San Mehat <san@google.com>
diff --git a/Android.mk b/Android.mk
index 1243ad7..d90b399 100644
--- a/Android.mk
+++ b/Android.mk
@@ -23,7 +23,8 @@
                   ProcessKiller.c                      \
                   geom_mbr_enc.c                       \
                   Fat.cpp                              \
-                  Loop.cpp
+                  Loop.cpp                             \
+                  Devmapper.cpp
 
 LOCAL_MODULE:= vold