make tests portable by using 565 compatible colors

TBR=reed@google.com

Review URL: https://codereview.chromium.org/1262703002
diff --git a/gm/fatpathfill.cpp b/gm/fatpathfill.cpp
index 43e1005..711d713 100644
--- a/gm/fatpathfill.cpp
+++ b/gm/fatpathfill.cpp
@@ -21,7 +21,7 @@
 
 static void draw_pixel_centers(SkCanvas* canvas) {
     SkPaint paint;
-    paint.setColor(0xFF0088FF);
+    paint.setColor(sk_tool_utils::color_to_565(0xFF0088FF));
     paint.setAntiAlias(true);
 
     for (int y = 0; y < SMALL_H; ++y) {