[NaCl SDK] Fix bug in archive step introduced in r133963

BUG=none
TEST=none
TBR=binji@chromium.org

Review URL: https://chromiumcodereview.appspot.com/10191025

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@133973 0039d316-1c4b-4281-b951-d872f2087c98

native_client_sdk/src/build_tools/build_sdk.py

@@ -684,7 +684,8 @@ def main(args):
     buildbot_common.BuildStep('Archive build')
     bucket_path = 'nativeclient-mirror/nacl/nacl_sdk/%s' % \
         build_utils.ChromeVersion()
-    buildbot_common.Archive(tarname, bucket_path, OUT_DIR)
+    buildbot_common.Archive(os.path.relpath(tarfile, OUT_DIR),
+                            bucket_path, OUT_DIR)
 
     # generate "manifest snippet" for this archive.
     if not skip_test_updater: