Switch from _DEBUG to NDEBUG.

core/include/fxcrt/fx_system.h

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #ifndef CORE_INCLUDE_FXCRT_FX_SYSTEM_H_
 #define CORE_INCLUDE_FXCRT_FX_SYSTEM_H_
 
 #include <assert.h>
@@ skipping 63 matching lines @@
 typedef double FX_DOUBLE;        // Keep, allow downgrade to floats.
 typedef int FX_BOOL;             // Keep, sadly not always 0 or 1.
 typedef char FX_CHAR;            // Keep, questionable signedness.
 typedef wchar_t FX_WCHAR;        // Keep, maybe bad platform wchars.
 
 // PDFium string sizes are limited to 2^31-1, and the value is signed to
 // allow -1 as a placeholder for "unknown".
 // TODO(palmer): it should be a |size_t|, or at least unsigned.
 typedef int FX_STRSIZE;
 
-#if defined(DEBUG) && !defined(_DEBUG)
-#define _DEBUG
-#endif
-
 #ifndef TRUE
 #define TRUE 1
 #endif
 
 #ifndef FALSE
 #define FALSE 0
 #endif
 
 #ifdef __cplusplus
 static_assert(TRUE == true, "true_needs_to_be_true");
 static_assert(FALSE == false, "false_needs_to_be_false");
 #endif
 
 #ifndef NULL
 #define NULL 0
 #endif
 
 #define FXSYS_assert assert
 #ifndef ASSERT
-#ifdef _DEBUG
+#ifndef NDEBUG
 #define ASSERT FXSYS_assert
 #else
 #define ASSERT(a)
 #endif
 #endif
 
 // M_PI not universally present on all platforms.
 #define FX_PI 3.1415926535897932384626433832795f
 #define FX_BEZIER 0.5522847498308f
 
@@ skipping 195 matching lines @@
 
 // Prevent a function from ever being inlined, typically because we'd
 // like it to appear in stack traces.
 #if _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_
 #define NEVER_INLINE __declspec(noinline)
 #else  // _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_
 #define NEVER_INLINE __attribute__((__noinline__))
 #endif  // _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_
 
 #endif  // CORE_INCLUDE_FXCRT_FX_SYSTEM_H_