Add an include guard to SkottieShaper.h

SkottieShaper.h was not protected against multiple inclusions in the
same translation unit.

Change-Id: Ie1f5acbcab82b9b1c37868739fb4322c471886cf
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/204421
Auto-Submit: bratell <bratell@opera.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>

modules/skottie/src/SkottieShaper.h

@@ -5,6 +5,9 @@
  * found in the LICENSE file.
  */
 
+#ifndef SkottieShaper_DEFINED
+#define SkottieShaper_DEFINED
+
 #include "SkPoint.h"
 #include "SkTextUtils.h"
 
@@ -46,3 +49,5 @@ private:
 };
 
 } // namespace skottie
+
+#endif // SkottieShaper_DEFINED