tweak octal numbers style to work with python-3

BUG=None
TEST=`./run_tests` passed

Change-Id: Ife102f80efdb5e040dc2ba96ac7aa4ee3f7a6c75
Reviewed-on: https://chromium-review.googlesource.com/173729
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
diff --git a/scripts/cros_generate_breakpad_symbols.py b/scripts/cros_generate_breakpad_symbols.py
index d69f375..1005c7e 100644
--- a/scripts/cros_generate_breakpad_symbols.py
+++ b/scripts/cros_generate_breakpad_symbols.py
@@ -145,7 +145,7 @@
                             header.name + '.sym')
     osutils.SafeMakedirs(os.path.dirname(sym_file))
     os.rename(temp.name, sym_file)
-    os.chmod(sym_file, 0644)
+    os.chmod(sym_file, 0o644)
     temp.delete = False
 
   return num_errors.value