Frameworks/base: Fix two warnings in cmds

Change-Id: Ifb9c7fb7a2d28c13010ddc186bea5f5f0daefb4a
diff --git a/cmds/backup/backup.cpp b/cmds/backup/backup.cpp
index 03ceffae0..8d9b528 100644
--- a/cmds/backup/backup.cpp
+++ b/cmds/backup/backup.cpp
@@ -75,7 +75,7 @@
                 size_t dataSize;
                 err = reader.ReadEntityHeader(&key, &dataSize);
                 if (err == 0) {
-                    printf("   entity: %s (%d bytes)\n", key.string(), dataSize);
+                    printf("   entity: %s (%zu bytes)\n", key.string(), dataSize);
                 } else {
                     printf("   Error reading entity header\n");
                 }