fix mac all build

tests/skia_test.cpp

Index: tests/skia_test.cpp
diff --git a/tests/skia_test.cpp b/tests/skia_test.cpp
index a1c3c237810fc8f42e1f45189201ceaadb0f8dc2..2b11e3ab50f37d51af3390577add64042c40381c 100644
--- a/tests/skia_test.cpp
+++ b/tests/skia_test.cpp
@@ -96,7 +96,7 @@ public:
               SkDebugf("\nFAILED: %s", failure.toString().c_str());
               fError = true;
           }
-          void* stats() { return fStats; }
+          void* stats() const override { return fStats; }
           void* fStats;
           bool fError;
           int fTestCount;