Switch usage of _DEBUG macro to NDEBUG.

webrtc/libjingle/xmpp/xmppclient.cc

Index: webrtc/libjingle/xmpp/xmppclient.cc
diff --git a/webrtc/libjingle/xmpp/xmppclient.cc b/webrtc/libjingle/xmpp/xmppclient.cc
index 7c2a5e693c51db5b35dff989321f8b552f6fe796..f7e88c39278610f446460c8ca3a56a3df673d06c 100644
--- a/webrtc/libjingle/xmpp/xmppclient.cc
+++ b/webrtc/libjingle/xmpp/xmppclient.cc
@@ -362,7 +362,7 @@ void XmppClient::Private::OnSocketRead() {
     if (bytes_read == 0)
       return;
 
-//#ifdef _DEBUG
+//#if !defined(NDEBUG)
     client_->SignalLogInput(bytes, static_cast<int>(bytes_read));
 //#endif
 
@@ -386,7 +386,7 @@ void XmppClient::Private::OnStateChange(int state) {
 }
 
 void XmppClient::Private::WriteOutput(const char* bytes, size_t len) {
-//#ifdef _DEBUG
+//#if !defined(NDEBUG)
   client_->SignalLogOutput(bytes, static_cast<int>(len));
 //#endif