Revert "Revert "Revert "remove (empty) SkXfermode.h"""

This reverts commit 1c038af278a69186e988dd9348b4089d78759492.

Reason for revert: <INSERT REASONING HERE>

More breaks in g3 (e.g. blink_headless)

Original change's description:
> Revert "Revert "remove (empty) SkXfermode.h""
> 
> This reverts commit c5d0147717e50acba106b76c6c345192274ddc06.
> 
> g3 is updated to allow this to land
> 
> BUG=skia:
> 
> Change-Id: I5f4b06c2dc77dfa66d9b32348375151177511a65
> Reviewed-on: https://skia-review.googlesource.com/5406
> Reviewed-by: Mike Reed <reed@google.com>
> Commit-Queue: Mike Reed <reed@google.com>
> 

TBR=reed@google.com,reviews@skia.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Change-Id: I77f69512f616120382c31d90243f7df13985d76c
Reviewed-on: https://skia-review.googlesource.com/5419
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Mike Reed <reed@google.com>
diff --git a/include/core/SkXfermode.h b/include/core/SkXfermode.h
new file mode 100644
index 0000000..199dff2
--- /dev/null
+++ b/include/core/SkXfermode.h
@@ -0,0 +1,13 @@
+/*
+ * Copyright 2006 The Android Open Source Project
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkXfermode_DEFINED
+#define SkXfermode_DEFINED
+
+//#error "SkXfermode.h is deprecated"
+
+#endif