Multi-user external storage support.

Remount rootfs as recursively shared, so that mount changes are
propagated into child namespaces.  Mount external storage for access
from adb.

Clean multi-user dependencies for use in Dalvik.  Also define
external storage paths.

Bug: 6925012
Change-Id: I375de581a63f4f36667894c56a34a9dd45361e8f
diff --git a/libcutils/Android.mk b/libcutils/Android.mk
index 2477d23..6d525ba 100644
--- a/libcutils/Android.mk
+++ b/libcutils/Android.mk
@@ -50,7 +50,8 @@
 	threads.c \
 	sched_policy.c \
 	iosched_policy.c \
-	str_parms.c
+	str_parms.c \
+	multiuser.c
 
 commonHostSources := \
         ashmem-host.c
@@ -124,8 +125,7 @@
         mq.c \
         partition_utils.c \
         qtaguid.c \
-        uevent.c \
-        multiuser.c
+        uevent.c
 
 ifeq ($(TARGET_ARCH),arm)
 LOCAL_SRC_FILES += arch-arm/memset32.S