Replace a lot of 'static const' with 'constexpr' or 'const'.

gm/strokerect.cpp

Index: gm/strokerect.cpp
diff --git a/gm/strokerect.cpp b/gm/strokerect.cpp
index 7b14854d76cb6a6f837d00fe5312bf4bef89b715..1d5d803ca625a41e78462f9f1dba7e22797db269 100644
--- a/gm/strokerect.cpp
+++ b/gm/strokerect.cpp
@@ -63,13 +63,13 @@ protected:
         paint.setStyle(SkPaint::kStroke_Style);
         paint.setStrokeWidth(STROKE_WIDTH);
 
-        static const SkPaint::Join gJoins[] = {
+        constexpr SkPaint::Join gJoins[] = {
             SkPaint::kMiter_Join, SkPaint::kRound_Join, SkPaint::kBevel_Join
         };
 
-        static const SkScalar W = 80;
-        static const SkScalar H = 80;
-        static const SkRect gRects[] = {
+        constexpr SkScalar W = 80;
+        constexpr SkScalar H = 80;
+        constexpr SkRect gRects[] = {
             { 0, 0, W, H },
             { W, 0, 0, H },
             { 0, H, W, 0 },