Misc warning fixes.

llvm-svn: 108029
diff --git a/lldb/tools/driver/IOChannel.cpp b/lldb/tools/driver/IOChannel.cpp
index d0bea70..06d1004 100644
--- a/lldb/tools/driver/IOChannel.cpp
+++ b/lldb/tools/driver/IOChannel.cpp
@@ -381,7 +381,7 @@
 bool
 IOChannel::Stop ()
 {
-    if (m_read_thread == NULL)
+    if (m_read_thread == LLDB_INVALID_HOST_THREAD)
         return true;
 
     BroadcastEventByType (eBroadcastBitThreadShouldExit);