Tiny fix to check_include_guards script
diff --git a/tools/distrib/check_include_guards.py b/tools/distrib/check_include_guards.py
index 897a899..890c75f 100755
--- a/tools/distrib/check_include_guards.py
+++ b/tools/distrib/check_include_guards.py
@@ -97,6 +97,7 @@
     match = self.ifndef_re.search(fcontents)
     if not match:
       print 'something drastically wrong with: %s' % fpath
+      return False # failed
     if match.lastindex is None:
       # No ifndef. Request manual addition with hints
       self.fail(fpath, match.re, match.string, '', '', False)