Add GYP target for sk_tool_utils.* component.

tools/sk_tool_utils.h

Index: tools/sk_tool_utils.h
diff --git a/tools/sk_tool_utils.h b/tools/sk_tool_utils.h
index 48fd716342b549dab6ad429119f9b151e6e88cc4..2bd42b607668be23ea8378b323e195bb932285cd 100644
--- a/tools/sk_tool_utils.h
+++ b/tools/sk_tool_utils.h
@@ -8,8 +8,10 @@
 #ifndef sk_tool_utils_DEFINED
 #define sk_tool_utils_DEFINED
 
-#include "SkCanvas.h"
-#include "SkBitmap.h"
+#include "SkImageInfo.h"
+
+class SkBitmap;
+class SkCanvas;
 
 namespace sk_tool_utils {
 
@@ -20,6 +22,7 @@ namespace sk_tool_utils {
      *  the pixels are colorType + alphaType
      */
     void write_pixels(SkCanvas*, const SkBitmap&, int x, int y, SkColorType, SkAlphaType);
-}
 
-#endif
+}  // namespace sk_tool_utils
+
+#endif  // sk_tool_utils_DEFINED