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/fastboot/Android.bp b/fastboot/Android.bp
index 884856d..3a2deb7 100644
--- a/fastboot/Android.bp
+++ b/fastboot/Android.bp
@@ -145,6 +145,7 @@
     static_libs: [
         "libhealthhalutils",
         "libsnapshot_nobinder",
+        "update_metadata-protos",
     ],
 
     header_libs: [