[PATCH] [ASan] Don't crash in DescribeHeapAddress if we don't know the current thread's ID

[Kostya Serebryany]

  LGTM


================
Comment at: asan_report.cc:447
@@ +446,3 @@
+  DescribeThread(GetCurrentThread());
+  if (free_thread)
+    DescribeThread(free_thread);
----------------
you don't need this if, do you? 


http://llvm-reviews.chandlerc.com/D1635