eliminate SK_BUILD_FOR_WIN32

SK_BUILD_FOR_WIN and SK_BUILD_FOR_WIN32 have long meant the same thing.

Chrome fix is https://chromium-review.googlesource.com/c/chromium/src/+/884007

Change-Id: I0e907b1bcd2a358eabf776f414fd3aeb3c689561
Reviewed-on: https://skia-review.googlesource.com/99340
Reviewed-by: Mike Reed <reed@google.com>
diff --git a/src/utils/win/SkWGL_win.cpp b/src/utils/win/SkWGL_win.cpp
index 0c1752a..b7c8994 100644
--- a/src/utils/win/SkWGL_win.cpp
+++ b/src/utils/win/SkWGL_win.cpp
@@ -6,7 +6,7 @@
  */
 
 #include "SkTypes.h"
-#if defined(SK_BUILD_FOR_WIN32)
+#if defined(SK_BUILD_FOR_WIN)
 
 #include "SkWGL.h"
 
@@ -503,4 +503,4 @@
     , fGLRC(glrc) {
 }
 
-#endif//defined(SK_BUILD_FOR_WIN32)
+#endif//defined(SK_BUILD_FOR_WIN)