libsnapshot clients: Add missing dep.

libsnapshot* uses update_metadata-protos. This
used to be optimized out, but now that SnapshotManager is
virtual, CreateUpdateSnapshots can no longer be optimized out.

Bug: 148956645
Test: compiles
Change-Id: Ib67cafd156308bf5a477996ec32eb786f8e896db
diff --git a/init/Android.mk b/init/Android.mk
index 416b732..da94daf 100644
--- a/init/Android.mk
+++ b/init/Android.mk
@@ -113,6 +113,7 @@
     libext2_uuid \
     libprotobuf-cpp-lite \
     libsnapshot_init \
+    update_metadata-protos \
 
 LOCAL_SANITIZE := signed-integer-overflow
 # First stage init is weird: it may start without stdout/stderr, and no /proc.