Add missing overrides to clear and discard batch dumpInfo()

src/gpu/batches/GrDiscardBatch.h

Index: src/gpu/batches/GrDiscardBatch.h
diff --git a/src/gpu/batches/GrDiscardBatch.h b/src/gpu/batches/GrDiscardBatch.h
index 9d9570fe85ec9b84e141794df795df31fa5e96ec..8a050a7122ca4e0978104574f05bba6476cdf16a 100644
--- a/src/gpu/batches/GrDiscardBatch.h
+++ b/src/gpu/batches/GrDiscardBatch.h
@@ -25,7 +25,7 @@ public:
 
     uint32_t renderTargetUniqueID() const override { return fRenderTarget.get()->getUniqueID(); }
 
-    SkString dumpInfo() const {
+    SkString dumpInfo() const override {
         SkString string;
         string.printf("RT: 0x%p", fRenderTarget.get());
         return string;