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

gm/complexclip2.cpp

Index: gm/complexclip2.cpp
diff --git a/gm/complexclip2.cpp b/gm/complexclip2.cpp
index 4314619cfdb34af4fe235b1e3095fae9c02ce9a0..2994e689eb430e24b9c6f7a7b26ed899fada7776 100644
--- a/gm/complexclip2.cpp
+++ b/gm/complexclip2.cpp
@@ -102,10 +102,10 @@ protected:
         }
     }
 
-    static const int kRows = 5;
-    static const int kCols = 5;
-    static const int kPadX = 20;
-    static const int kPadY = 20;
+    static constexpr int kRows = 5;
+    static constexpr int kCols = 5;
+    static constexpr int kPadX = 20;
+    static constexpr int kPadY = 20;
 
     static const char* ClipStr(Clip clip) {
         switch (clip) {