Update webrtc/base/common.h after recent _DEBUG->!NDEBUG change.

R=tfarina@chromium.org
TBR=tfarina@chromium.org
BUG=

Review URL: https://codereview.webrtc.org/1410113007 .

Cr-Commit-Position: refs/heads/master@{#10470}
diff --git a/webrtc/base/common.h b/webrtc/base/common.h
index e615c76..67665f2 100644
--- a/webrtc/base/common.h
+++ b/webrtc/base/common.h
@@ -61,7 +61,11 @@
 /////////////////////////////////////////////////////////////////////////////
 
 #ifndef ENABLE_DEBUG
-#define ENABLE_DEBUG _DEBUG
+#if !defined(NDEBUG)
+#define ENABLE_DEBUG 1
+#else
+#define ENABLE_DEBUG 0
+#endif
 #endif  // !defined(ENABLE_DEBUG)
 
 // Even for release builds, allow for the override of LogAssert. Though no