Start making all .cpp files compile-able on all platforms.

src/ports/SkTypeface_win_dw.cpp

Index: src/ports/SkTypeface_win_dw.cpp
diff --git a/src/ports/SkTypeface_win_dw.cpp b/src/ports/SkTypeface_win_dw.cpp
index 144d4c7367bdaa77586478367e1730fef59ef9bf..38d09e85ecf25a0aaeeef023a2f7d16495b5637c 100644
--- a/src/ports/SkTypeface_win_dw.cpp
+++ b/src/ports/SkTypeface_win_dw.cpp
@@ -6,6 +6,8 @@
  */
 
 #include "SkTypes.h"
+#if defined(SK_BUILD_FOR_WIN32)
+
 // SkTypes will include Windows.h, which will pull in all of the GDI defines.
 // GDI #defines GetGlyphIndices to GetGlyphIndicesA or GetGlyphIndicesW, but
 // IDWriteFontFace has a method called GetGlyphIndices. Since this file does
@@ -459,3 +461,4 @@ SkAdvancedTypefaceMetrics* DWriteFontTypeface::onGetAdvancedTypefaceMetrics(
 
     return info;
 }
+#endif//defined(SK_BUILD_FOR_WIN32)