spin off easy stuff from Herb's windows GN CL

include/c/sk_types.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 // EXPERIMENTAL EXPERIMENTAL EXPERIMENTAL EXPERIMENTAL
 // DO NOT USE -- FOR INTERNAL TESTING ONLY
 
 #ifndef sk_types_DEFINED
 #define sk_types_DEFINED
 
 #include <stdint.h>
 #include <stddef.h>
 
 #ifdef __cplusplus
     #define SK_C_PLUS_PLUS_BEGIN_GUARD    extern "C" {
     #define SK_C_PLUS_PLUS_END_GUARD      }
 #else
     #include <stdbool.h>
     #define SK_C_PLUS_PLUS_BEGIN_GUARD
     #define SK_C_PLUS_PLUS_END_GUARD
 #endif
 
 #if !defined(SK_API)
     #if defined(SKIA_DLL)
-        #if defined(SK_BUILD_FOR_WIN32)
+        #if defined(_MSC_VER)
             #if SKIA_IMPLEMENTATION
                 #define SK_API __declspec(dllexport)
             #else
                 #define SK_API __declspec(dllimport)
             #endif
         #else
             #define SK_API __attribute__((visibility("default")))
         #endif
     #else
         #define SK_API
@@ skipping 169 matching lines @@
     SATURATION_SK_XFERMODE_MODE,
     COLOR_SK_XFERMODE_MODE,
     LUMINOSITY_SK_XFERMODE_MODE,
 } sk_xfermode_mode_t;
 
 //////////////////////////////////////////////////////////////////////////////////////////
 
 SK_C_PLUS_PLUS_END_GUARD
 
 #endif