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/ports/SkOSFile_win.cpp b/src/ports/SkOSFile_win.cpp
index 50ca264..05afcc6 100644
--- a/src/ports/SkOSFile_win.cpp
+++ b/src/ports/SkOSFile_win.cpp
@@ -6,7 +6,7 @@
  */
 
 #include "SkTypes.h"
-#if defined(SK_BUILD_FOR_WIN32)
+#if defined(SK_BUILD_FOR_WIN)
 
 #include "SkLeanWindows.h"
 #include "SkMalloc.h"
@@ -273,4 +273,4 @@
     return self.fHandle != (HANDLE)~0 && get_the_file(self.fHandle, name, dataPtr, getDir);
 }
 
-#endif//defined(SK_BUILD_FOR_WIN32)
+#endif//defined(SK_BUILD_FOR_WIN)