cmd/cgo: use standard generated code comment

Change cgo to follow https://golang.org/s/generatedcode.

For the C code we continue to use /* */ comments, so they don't follow
the format exactly. It doesn't really matter since the format is only
for Go code anyhow. This CL changes the C code to be similar for
consistency.

Fixes #25623

Change-Id: Idcfee53ec4069924d173ab8cedeb7bcfb7312863
Reviewed-on: https://go-review.googlesource.com/115035
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>

src/cmd/cgo/godefs.go

@@ -19,7 +19,7 @@ import (
 func (p *Package) godefs(f *File, srcfile string) string {
 	var buf bytes.Buffer
 
-	fmt.Fprintf(&buf, "// Created by cgo -godefs - DO NOT EDIT\n")
+	fmt.Fprintf(&buf, "// Code generated by cmd/cgo -godefs; DO NOT EDIT.\n")
 	fmt.Fprintf(&buf, "// %s %s\n", filepath.Base(os.Args[0]), strings.Join(os.Args[1:], " "))
 	fmt.Fprintf(&buf, "\n")
 

src/cmd/cgo/out.go

@@ -73,7 +73,7 @@ func (p *Package) writeDefs() {
 	// Write second Go output: definitions of _C_xxx.
 	// In a separate file so that the import of "unsafe" does not
 	// pollute the original file.
-	fmt.Fprintf(fgo2, "// Created by cgo - DO NOT EDIT\n\n")
+	fmt.Fprintf(fgo2, "// Code generated by cmd/cgo; DO NOT EDIT.\n\n")
 	fmt.Fprintf(fgo2, "package %s\n\n", p.PackageName)
 	fmt.Fprintf(fgo2, "import \"unsafe\"\n\n")
 	if !*gccgo && *importRuntimeCgo {
@@ -536,7 +536,7 @@ func (p *Package) writeOutput(f *File, srcfile string) {
 	p.GccFiles = append(p.GccFiles, base+".cgo2.c")
 
 	// Write Go output: Go input with rewrites of C.xxx to _C_xxx.
-	fmt.Fprintf(fgo1, "// Created by cgo - DO NOT EDIT\n\n")
+	fmt.Fprintf(fgo1, "// Code generated by cmd/cgo; DO NOT EDIT.\n\n")
 	fmt.Fprintf(fgo1, "//line %s:1\n", srcfile)
 	fgo1.Write(f.Edit.Bytes())
 
@@ -740,7 +740,7 @@ func (p *Package) packedAttribute() string {
 func (p *Package) writeExports(fgo2, fm, fgcc, fgcch io.Writer) {
 	p.writeExportHeader(fgcch)
 
-	fmt.Fprintf(fgcc, "/* Created by cgo - DO NOT EDIT. */\n")
+	fmt.Fprintf(fgcc, "/* Code generated by cmd/cgo; DO NOT EDIT. */\n\n")
 	fmt.Fprintf(fgcc, "#include <stdlib.h>\n")
 	fmt.Fprintf(fgcc, "#include \"_cgo_export.h\"\n\n")
 
@@ -981,7 +981,7 @@ func (p *Package) writeGccgoExports(fgo2, fm, fgcc, fgcch io.Writer) {
 
 	p.writeExportHeader(fgcch)
 
-	fmt.Fprintf(fgcc, "/* Created by cgo - DO NOT EDIT. */\n")
+	fmt.Fprintf(fgcc, "/* Code generated by cmd/cgo; DO NOT EDIT. */\n\n")
 	fmt.Fprintf(fgcc, "#include \"_cgo_export.h\"\n")
 
 	fmt.Fprintf(fgcc, "%s\n", gccgoExportFileProlog)
@@ -1147,7 +1147,7 @@ func (p *Package) writeGccgoExports(fgo2, fm, fgcc, fgcch io.Writer) {
 
 // writeExportHeader writes out the start of the _cgo_export.h file.
 func (p *Package) writeExportHeader(fgcch io.Writer) {
-	fmt.Fprintf(fgcch, "/* Created by \"go tool cgo\" - DO NOT EDIT. */\n\n")
+	fmt.Fprintf(fgcch, "/* Code generated by cmd/cgo; DO NOT EDIT. */\n\n")
 	pkg := *importPath
 	if pkg == "" {
 		pkg = p.PackagePath