builder: Adjust usage of shlex.ProcessWord

1b1c5bc08ad81add007eb647e66ed0929693f3a0 extended the function signature
with one additional return value.

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>

builder/dockerfile/builder.go

@@ -230,7 +230,8 @@ func processMetaArg(meta instructions.ArgCommand, shlex *shell.Lex, args *BuildA
 	// shell.Lex currently only support the concatenated string format
 	envs := convertMapToEnvList(args.GetAllAllowed())
 	if err := meta.Expand(func(word string) (string, error) {
-		return shlex.ProcessWord(word, envs)
+		newword, _, err := shlex.ProcessWord(word, envs)
+		return newword, err
 	}); err != nil {
 		return err
 	}

builder/dockerfile/dispatchers.go

@@ -224,7 +224,7 @@ func (d *dispatchRequest) getExpandedString(shlex *shell.Lex, str string) (strin
 		substitutionArgs = append(substitutionArgs, key+"="+value)
 	}
 
-	name, err := shlex.ProcessWord(str, substitutionArgs)
+	name, _, err := shlex.ProcessWord(str, substitutionArgs)
 	if err != nil {
 		return "", err
 	}

builder/dockerfile/evaluator.go

@@ -48,7 +48,8 @@ func dispatch(ctx context.Context, d dispatchRequest, cmd instructions.Command)
 
 	if ex, ok := cmd.(instructions.SupportsSingleWordExpansion); ok {
 		err := ex.Expand(func(word string) (string, error) {
-			return d.shlex.ProcessWord(word, envs)
+			newword, _, err := d.shlex.ProcessWord(word, envs)
+			return newword, err
 		})
 		if err != nil {
 			return errdefs.InvalidParameter(err)