Fix arguments to d8.py from the build_sample

Change-Id: I60ae13482b4e627fa2e9166bde5b5dd5a5886690
diff --git a/tools/build_sample_apk.py b/tools/build_sample_apk.py
index a08a4ec..376c5c0 100755
--- a/tools/build_sample_apk.py
+++ b/tools/build_sample_apk.py
@@ -159,7 +159,7 @@
   for root, dirnames, filenames in os.walk(get_bin_path(app)):
     for filename in fnmatch.filter(filenames, '*.class'):
         files.append(os.path.join(root, filename))
-  command = [DEFAULT_D8,
+  command = [DEFAULT_D8, '--',
              '--output', get_bin_path(app),
              '--classpath', utils.get_android_jar(api),
              '--min-api', str(api)]