Switch usage of _DEBUG macro to NDEBUG.

webrtc/base/openssladapter.cc

Index: webrtc/base/openssladapter.cc
diff --git a/webrtc/base/openssladapter.cc b/webrtc/base/openssladapter.cc
index c906ebb4b49b27e302886aa1c3088879d84f2659..892b5ccb41441948b5fa189539f93b6234f91d0b 100644
--- a/webrtc/base/openssladapter.cc
+++ b/webrtc/base/openssladapter.cc
@@ -835,7 +835,7 @@ bool OpenSSLAdapter::SSLPostConnectionCheck(SSL* ssl, const char* host) {
   return ok;
 }
 
-#if _DEBUG
+#if !defined(NDEBUG)
 
 // We only use this for tracing and so it is only needed in debug mode
 
@@ -864,11 +864,11 @@ OpenSSLAdapter::SSLInfoCallback(const SSL* s, int where, int ret) {
   }
 }
 
-#endif  // _DEBUG
+#endif
 
 int
 OpenSSLAdapter::SSLVerifyCallback(int ok, X509_STORE_CTX* store) {
-#if _DEBUG
+#if !defined(NDEBUG)
   if (!ok) {
     char data[256];
     X509* cert = X509_STORE_CTX_get_current_cert(store);
@@ -949,7 +949,7 @@ OpenSSLAdapter::SetupSSLContext() {
     return NULL;
   }
 
-#ifdef _DEBUG
+#if !defined(NDEBUG)
   SSL_CTX_set_info_callback(ctx, SSLInfoCallback);
 #endif