Revert vendor directory to support old golang (GOPATH mode)

gomodule is still in progress to migrate for now, hence multus
team decide to keep vendor directory to support build without
gomodule.

vendor/github.com/spf13/pflag/string.go

@@ -0,0 +1,80 @@
+package pflag
+
+// -- string Value
+type stringValue string
+
+func newStringValue(val string, p *string) *stringValue {
+	*p = val
+	return (*stringValue)(p)
+}
+
+func (s *stringValue) Set(val string) error {
+	*s = stringValue(val)
+	return nil
+}
+func (s *stringValue) Type() string {
+	return "string"
+}
+
+func (s *stringValue) String() string { return string(*s) }
+
+func stringConv(sval string) (interface{}, error) {
+	return sval, nil
+}
+
+// GetString return the string value of a flag with the given name
+func (f *FlagSet) GetString(name string) (string, error) {
+	val, err := f.getFlagType(name, "string", stringConv)
+	if err != nil {
+		return "", err
+	}
+	return val.(string), nil
+}
+
+// StringVar defines a string flag with specified name, default value, and usage string.
+// The argument p points to a string variable in which to store the value of the flag.
+func (f *FlagSet) StringVar(p *string, name string, value string, usage string) {
+	f.VarP(newStringValue(value, p), name, "", usage)
+}
+
+// StringVarP is like StringVar, but accepts a shorthand letter that can be used after a single dash.
+func (f *FlagSet) StringVarP(p *string, name, shorthand string, value string, usage string) {
+	f.VarP(newStringValue(value, p), name, shorthand, usage)
+}
+
+// StringVar defines a string flag with specified name, default value, and usage string.
+// The argument p points to a string variable in which to store the value of the flag.
+func StringVar(p *string, name string, value string, usage string) {
+	CommandLine.VarP(newStringValue(value, p), name, "", usage)
+}
+
+// StringVarP is like StringVar, but accepts a shorthand letter that can be used after a single dash.
+func StringVarP(p *string, name, shorthand string, value string, usage string) {
+	CommandLine.VarP(newStringValue(value, p), name, shorthand, usage)
+}
+
+// String defines a string flag with specified name, default value, and usage string.
+// The return value is the address of a string variable that stores the value of the flag.
+func (f *FlagSet) String(name string, value string, usage string) *string {
+	p := new(string)
+	f.StringVarP(p, name, "", value, usage)
+	return p
+}
+
+// StringP is like String, but accepts a shorthand letter that can be used after a single dash.
+func (f *FlagSet) StringP(name, shorthand string, value string, usage string) *string {
+	p := new(string)
+	f.StringVarP(p, name, shorthand, value, usage)
+	return p
+}
+
+// String defines a string flag with specified name, default value, and usage string.
+// The return value is the address of a string variable that stores the value of the flag.
+func String(name string, value string, usage string) *string {
+	return CommandLine.StringP(name, "", value, usage)
+}
+
+// StringP is like String, but accepts a shorthand letter that can be used after a single dash.
+func StringP(name, shorthand string, value string, usage string) *string {
+	return CommandLine.StringP(name, shorthand, value, usage)
+}