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

src/doc/SkDocument_XPS_None.cpp

Index: src/doc/SkDocument_XPS_None.cpp
diff --git a/src/doc/SkDocument_XPS_None.cpp b/src/doc/SkDocument_XPS_None.cpp
index 9d51ea25d7ee9f64c3db2224ef3d82c3a8890900..32b18fb221caa30c15263e6e6b1640fbf11bf5c3 100644
--- a/src/doc/SkDocument_XPS_None.cpp
+++ b/src/doc/SkDocument_XPS_None.cpp
@@ -4,6 +4,12 @@
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
+
+#include "SkTypes.h"
+#if !defined(SK_BUILD_FOR_WIN32)
+
 #include "SkDocument.h"
 SkDocument* SkDocument::CreateXPS(SkWStream*, SkScalar) { return nullptr; }
 SkDocument* SkDocument::CreateXPS(const char path[], SkScalar) { return nullptr; }
+
+#endif//!defined(SK_BUILD_FOR_WIN32)