Further reduce the number of primitives in the donut tests. Avoids crashes on iOS.

BUG=skia:4937
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1691813002

Review URL: https://codereview.chromium.org/1691813002
diff --git a/bench/ShapesBench.cpp b/bench/ShapesBench.cpp
index 1a3702f..07f7d56 100644
--- a/bench/ShapesBench.cpp
+++ b/bench/ShapesBench.cpp
@@ -276,13 +276,13 @@
 // Donuts (small and large). These fall-back to path rendering due to non-orthogonal rotation
 // making them quite slow. Thus, reduce the counts substantially:
 DEF_BENCH(return new ShapesBench(ShapesBench::kRect_ShapesType, ShapesBench::kRect_ShapesType,
-                                 2000, SkISize::Make(32, 32), false);)
+                                 500, SkISize::Make(32, 32), false);)
 DEF_BENCH(return new ShapesBench(ShapesBench::kRRect_ShapesType, ShapesBench::kRRect_ShapesType,
-                                 2000, SkISize::Make(32, 32), false);)
+                                 500, SkISize::Make(32, 32), false);)
 DEF_BENCH(return new ShapesBench(ShapesBench::kRect_ShapesType, ShapesBench::kRect_ShapesType,
-                                 200, SkISize::Make(500, 500), false);)
+                                 50, SkISize::Make(500, 500), false);)
 DEF_BENCH(return new ShapesBench(ShapesBench::kRRect_ShapesType, ShapesBench::kRRect_ShapesType,
-                                 200, SkISize::Make(500, 500), false);)
+                                 50, SkISize::Make(500, 500), false);)
 
 #if ENABLE_COMMAND_LINE_SHAPES_BENCH
 DEF_BENCH(return new ShapesBench;)