image/gif,image/jpeg,image/png: skip FuzzDecode in testing short mode

The image/gif.FuzzDecode takes an excessive amount of time to run on various
builders - skip these in testing short mode. Likewise for image/jpeg and
image/png.

Fixes #55839

Change-Id: I1049d06b9dcbbc7dbc4f53d3c49b64e2254eabbd
Reviewed-on: https://go-review.googlesource.com/c/go/+/435175
Reviewed-by: Roland Shoemaker <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Run-TryBot: Bryan Mills <[email protected]>
Reviewed-by: Bryan Mills <[email protected]>

Author: 4a6f656c

src/image/gif/fuzz_test.go

@@ -14,6 +14,10 @@ import (
 )
 
 func FuzzDecode(f *testing.F) {
+	if testing.Short() {
+		f.Skip("Skipping in short mode")
+	}
+
 	testdata, err := os.ReadDir("../testdata")
 	if err != nil {
 		f.Fatalf("failed to read testdata directory: %s", err)

src/image/jpeg/fuzz_test.go

@@ -14,6 +14,10 @@ import (
 )
 
 func FuzzDecode(f *testing.F) {
+	if testing.Short() {
+		f.Skip("Skipping in short mode")
+	}
+
 	testdata, err := os.ReadDir("../testdata")
 	if err != nil {
 		f.Fatalf("failed to read testdata directory: %s", err)

src/image/png/fuzz_test.go

@@ -14,6 +14,10 @@ import (
 )
 
 func FuzzDecode(f *testing.F) {
+	if testing.Short() {
+		f.Skip("Skipping in short mode")
+	}
+
 	testdata, err := os.ReadDir("../testdata")
 	if err != nil {
 		f.Fatalf("failed to read testdata directory: %s", err)