internal/cmd/deadcode: omit package/func keywords in default output

...and don't quote the package path.

Updates golang/go#63501

Change-Id: Ic4f52bf74d7ddd185f2179deed55118971bfa7ed
Reviewed-on: https://go-review.googlesource.com/c/tools/+/540218
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Findley <rfindley@google.com>

internal/cmd/deadcode/deadcode.go

@@ -308,9 +308,9 @@ func main() {
 			for _, fn := range pkg.Funcs {
 				if !seen {
 					seen = true
-					fmt.Printf("package %q\n", pkg.Path)
+					fmt.Println(pkg.Path)
 				}
-				fmt.Printf("\tfunc %s\n", fn.RelName)
+				fmt.Printf("\t%s\n", fn.RelName)
 			}
 			if seen {
 				fmt.Println()

internal/cmd/deadcode/doc.go

@@ -80,7 +80,7 @@ With the -format=template flag, the command executes the specified template
 on each Package record. So, this template produces a result similar to the
 default format:
 
-	-format='{{printf "package %q\n" .Path}}{{range .Funcs}}{{println "\tfunc " .RelName}}{{end}}{{println}}'
+	-format='{{println .Path}}{{range .Funcs}}{{printf "\t%s\n" .RelName}}{{end}}{{println}}'
 
 And this template shows only the list of source positions of dead functions:
 

internal/cmd/deadcode/testdata/basic.txtar

@@ -2,13 +2,13 @@
 
  deadcode -filter= example.com
 
- want "func (T).Goodbye"
-!want "func (T).Hello"
- want "func unreferenced"
+ want "(T).Goodbye"
+!want "(T).Hello"
+ want "unreferenced"
 
- want "func Scanf"
- want "func Printf"
-!want "func Println"
+ want "Scanf"
+ want "Printf"
+!want "Println"
 
 -- go.mod --
 module example.com

internal/cmd/deadcode/testdata/filterflag.txtar

@@ -2,12 +2,12 @@
 
  deadcode -filter=other.net example.com
 
- want `package "other.net"`
- want `func Dead`
-!want `func Live`
+ want `other.net`
+ want `Dead`
+!want `Live`
 
-!want `package "example.com"`
-!want `func unreferenced`
+!want `example.com`
+!want `unreferenced`
 
 -- go.work --
 use example.com

internal/cmd/deadcode/testdata/testflag.txtar

@@ -2,12 +2,12 @@
 
 deadcode -test -filter=example.com example.com/p
 
- want "func Dead"
-!want "func Live1"
-!want "func Live2"
+ want "Dead"
+!want "Live1"
+!want "Live2"
 
- want "func ExampleDead"
-!want "func ExampleLive"
+ want "ExampleDead"
+!want "ExampleLive"
 
 -- go.mod --
 module example.com