Return []byte from encode, use it instead of bytes.Buffer

We only use Buffer for its internal buffer returned by Bytes() outside
encode() anyway, so there's no reason to hold on to whole Buffer object.

internal/lvgen/procedures.tmpl

@@ -129,7 +129,7 @@ func decodeTypedParams(dec *xdr.Decoder) ([]TypedParam, error) {
 {{range .Procs}}
 // {{.Name}} is the go wrapper for {{.LVName}}.
 func (l *Libvirt) {{.Name}}({{range $ix, $arg := .Args}}{{if $ix}}, {{end}}{{.Name}} {{.Type}}{{end}}) ({{range .Ret}}r{{.Name}} {{.Type}}, {{end}}err error) {
-	var buf bytes.Buffer
+	var buf []byte
 {{if .ArgsStruct}}
 	args := {{.ArgsStruct}} {
 {{range .Args}}		{{.Name}}: {{.Name}},
@@ -141,7 +141,7 @@ func (l *Libvirt) {{.Name}}({{range $ix, $arg := .Args}}{{if $ix}}, {{end}}{{.Na
 	}
 {{end}}
 {{if .RetStruct}}	var r response{{end}}
-	{{if .RetStruct}}r{{else}}_{{end}}, err = l.request({{.Num}}, constants.Program, &buf)
+	{{if .RetStruct}}r{{else}}_{{end}}, err = l.request({{.Num}}, constants.Program, buf)
 	if err != nil {
 		return
 	}