move SkTPin to include/private

Change-Id: Ib0dc823d331a7cddc5da1d1be83136ce803a7871
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/327783
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Reed <reed@google.com>
diff --git a/tools/viewer/Viewer.cpp b/tools/viewer/Viewer.cpp
index 67c0dd3..d5ab9af 100644
--- a/tools/viewer/Viewer.cpp
+++ b/tools/viewer/Viewer.cpp
@@ -12,6 +12,7 @@
 #include "include/core/SkStream.h"
 #include "include/core/SkSurface.h"
 #include "include/gpu/GrDirectContext.h"
+#include "include/private/SkTPin.h"
 #include "include/private/SkTo.h"
 #include "include/utils/SkPaintFilterCanvas.h"
 #include "src/core/SkColorSpacePriv.h"