Support delete local instance in acloud deleted function.

Bug: 117474343
Test: m acloud && atest acloud_test && acloud delete
Change-Id: I925308163e5d55a1dbce1a11f13802557bd840f5
diff --git a/public/acloud_main.py b/public/acloud_main.py
index d4120a6..2e31da5 100644
--- a/public/acloud_main.py
+++ b/public/acloud_main.py
@@ -419,7 +419,7 @@
         sys.stderr.write("Invalid command %s" % args.which)
         return 2
 
-    if report:
+    if report and args.report_file:
         report.Dump(args.report_file)
         if report.errors:
             msg = "\n".join(report.errors)