Dump the native stack of an unattached aborting thread.

Useful when diagnosing errors in threads that have yet to become attached.

Change-Id: Id50b96d12f8c2e8a29e0606d15009287a554aa64
diff --git a/runtime/runtime.cc b/runtime/runtime.cc
index d78be92..8b8cf9f 100644
--- a/runtime/runtime.cc
+++ b/runtime/runtime.cc
@@ -202,6 +202,8 @@
     Thread* self = Thread::Current();
     if (self == nullptr) {
       os << "(Aborting thread was not attached to runtime!)\n";
+      DumpKernelStack(os, GetTid(), "  kernel: ", false);
+      DumpNativeStack(os, GetTid(), "  native: ", nullptr);
     } else {
       os << "Aborting thread:\n";
       if (Locks::mutator_lock_->IsExclusiveHeld(self) || Locks::mutator_lock_->IsSharedHeld(self)) {