Enable SK_DEBUG/SK_RELEASE to be defined in the user config.

include/core/SkPreConfig.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 // IWYU pragma: private, include "SkTypes.h"
 
 #ifndef SkPreConfig_DEFINED
@@ skipping 34 matching lines @@
  * the default (NDK-compliant) Android code. Therefore, when attempting to
  * include/exclude something from the framework variant check first that we are
  * building for Android then check the status of the framework define.
  */
 #if defined(SK_BUILD_FOR_ANDROID_FRAMEWORK) && !defined(SK_BUILD_FOR_ANDROID)
     #define SK_BUILD_FOR_ANDROID
 #endif
 
 //////////////////////////////////////////////////////////////////////
 
-#if !defined(SK_DEBUG) && !defined(SK_RELEASE)
-    #ifdef NDEBUG
-        #define SK_RELEASE
-    #else
-        #define SK_DEBUG
-    #endif
-#endif
-
 #ifdef SK_BUILD_FOR_WIN32
     #if !defined(SK_RESTRICT)
         #define SK_RESTRICT __restrict
     #endif
     #if !defined(SK_WARN_UNUSED_RESULT)
         #define SK_WARN_UNUSED_RESULT
     #endif
 #endif
 
-//////////////////////////////////////////////////////////////////////
-
 #if !defined(SK_RESTRICT)
     #define SK_RESTRICT __restrict__
 #endif
 
 #if !defined(SK_WARN_UNUSED_RESULT)
     #define SK_WARN_UNUSED_RESULT __attribute__((warn_unused_result))
 #endif
 
 //////////////////////////////////////////////////////////////////////
 
@@ skipping 179 matching lines @@
  *
  * NOTE: Clang/ARM (r161757) does not support the 'optimize' attribute.
  */
 #if SK_HAS_ATTRIBUTE(optimize)
 #   define SK_ATTRIBUTE_OPTIMIZE_O1 __attribute__((optimize("O1")))
 #else
 #   define SK_ATTRIBUTE_OPTIMIZE_O1 /* nothing */
 #endif
 
 #endif