Rationalize how we do Halt-ing before Destroy and Detach.

<rdar://problem/13527167>

llvm-svn: 178325
diff --git a/lldb/source/Target/StopInfo.cpp b/lldb/source/Target/StopInfo.cpp
index 54c1049..33ade1e 100644
--- a/lldb/source/Target/StopInfo.cpp
+++ b/lldb/source/Target/StopInfo.cpp
@@ -291,6 +291,8 @@
         {
             // This shouldn't ever happen, but just in case, don't do more harm.
             log->Printf ("PerformAction got called with an invalid thread.");
+            m_should_stop = true;
+            m_should_stop_is_valid = true;
             return;
         }