ART: Make verifier fail log level adjustable

To help for build failures.

Change-Id: I6c94dfb50177daa7d89902d78715ccec31bf0e45
diff --git a/runtime/base/logging.h b/runtime/base/logging.h
index 8aaeaac..97280c3 100644
--- a/runtime/base/logging.h
+++ b/runtime/base/logging.h
@@ -24,6 +24,7 @@
 namespace art {
 
 enum LogSeverity {
+  NONE,            // Fake level, don't log at all.
   VERBOSE,
   DEBUG,
   INFO,