Add 'adb backup' for pulling a full backup tarfile to the host

The direct command interfaces with the 'bu' binary in /system/bin
on the device.

Change-Id: I4cd69eedfe5144c47277573c5626c6ad8755d70b
diff --git a/adb/Android.mk b/adb/Android.mk
index 6ed31eb..e893ca9 100644
--- a/adb/Android.mk
+++ b/adb/Android.mk
@@ -113,6 +113,7 @@
 
 LOCAL_SRC_FILES := \
 	adb.c \
+	backup_service.c \
 	fdevent.c \
 	transport.c \
 	transport_local.c \
@@ -164,6 +165,7 @@
 
 LOCAL_SRC_FILES := \
 	adb.c \
+	backup_service.c \
 	console.c \
 	transport.c \
 	transport_local.c \