Tolerate NULL method in Thread::GetCurrentMethod

Change-Id: I99ad1ce7852d177a6bdd277570b1b1d710ae5d58
diff --git a/src/thread.cc b/src/thread.cc
index b828e94..a9dfc23 100644
--- a/src/thread.cc
+++ b/src/thread.cc
@@ -1411,7 +1411,7 @@
     m = f.GetMethod();
   }
   if (pc != NULL) {
-    *pc = ManglePc(f.GetReturnPC());
+    *pc = (m != NULL) ? ManglePc(f.GetReturnPC()) : 0;
   }
   if (sp != NULL) {
     *sp = f.GetSP();