image/png: remove go-fuzz test

An identical go1.18 test exists at `src/image/png/fuzz_test.go`.

Change-Id: I3e4db46296fb6a56655f849da8c0689aa5a1c28c
Reviewed-on: https://go-review.googlesource.com/c/go/+/576795
Reviewed-by: qiu laidongfeng2 <2645477756@qq.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>

src/image/png/fuzz.go

@@ -1,52 +0,0 @@
-// Copyright 2019 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build gofuzz
-
-package png
-
-import (
-	"bytes"
-	"fmt"
-)
-
-func Fuzz(data []byte) int {
-	cfg, err := DecodeConfig(bytes.NewReader(data))
-	if err != nil {
-		return 0
-	}
-	if cfg.Width*cfg.Height > 1e6 {
-		return 0
-	}
-	img, err := Decode(bytes.NewReader(data))
-	if err != nil {
-		return 0
-	}
-	levels := []CompressionLevel{
-		DefaultCompression,
-		NoCompression,
-		BestSpeed,
-		BestCompression,
-	}
-	for _, l := range levels {
-		var w bytes.Buffer
-		e := &Encoder{CompressionLevel: l}
-		err = e.Encode(&w, img)
-		if err != nil {
-			panic(err)
-		}
-		img1, err := Decode(&w)
-		if err != nil {
-			panic(err)
-		}
-		got := img1.Bounds()
-		want := img.Bounds()
-		if !got.Eq(want) {
-			fmt.Printf("bounds0: %#v\n", want)
-			fmt.Printf("bounds1: %#v\n", got)
-			panic("bounds have changed")
-		}
-	}
-	return 1
-}