Remove github.com/pkg/errors and replace with std library version

This is possible now that we no longer support go1.12 and brings
rclone into line with standard practices in the Go world.

This also removes errors.New and errors.Errorf from lib/errors and
prefers the stdlib errors package over lib/errors.

backend/pcloud/pcloud.go

@@ -10,6 +10,7 @@ package pcloud
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -18,7 +19,6 @@ import (
 	"strings"
 	"time"
 
-	"github.com/pkg/errors"
 	"github.com/rclone/rclone/backend/pcloud/api"
 	"github.com/rclone/rclone/fs"
 	"github.com/rclone/rclone/fs/config"
@@ -290,7 +290,7 @@ func NewFs(ctx context.Context, name, root string, m configmap.Mapper) (fs.Fs, e
 	root = parsePath(root)
 	oAuthClient, ts, err := oauthutil.NewClient(ctx, name, m, oauthConfig)
 	if err != nil {
-		return nil, errors.Wrap(err, "failed to configure Pcloud")
+		return nil, fmt.Errorf("failed to configure Pcloud: %w", err)
 	}
 	updateTokenURL(oauthConfig, opt.Hostname)
 
@@ -463,7 +463,7 @@ func (f *Fs) listAll(ctx context.Context, dirID string, directoriesOnly bool, fi
 		return shouldRetry(ctx, resp, err)
 	})
 	if err != nil {
-		return found, errors.Wrap(err, "couldn't list files")
+		return found, fmt.Errorf("couldn't list files: %w", err)
 	}
 	for i := range result.Metadata.Contents {
 		item := &result.Metadata.Contents[i]
@@ -600,7 +600,7 @@ func (f *Fs) purgeCheck(ctx context.Context, dir string, check bool) error {
 		return shouldRetry(ctx, resp, err)
 	})
 	if err != nil {
-		return errors.Wrap(err, "rmdir failed")
+		return fmt.Errorf("rmdir failed: %w", err)
 	}
 	f.dirCache.FlushDir(dir)
 	if err != nil {
@@ -872,7 +872,7 @@ func (f *Fs) About(ctx context.Context) (usage *fs.Usage, err error) {
 		return shouldRetry(ctx, resp, err)
 	})
 	if err != nil {
-		return nil, errors.Wrap(err, "about failed")
+		return nil, fmt.Errorf("about failed: %w", err)
 	}
 	usage = &fs.Usage{
 		Total: fs.NewUsageValue(q.Quota),               // quota of bytes that can be used
@@ -952,7 +952,7 @@ func (o *Object) Hash(ctx context.Context, t hash.Type) (string, error) {
 	if o.md5 == "" && o.sha1 == "" && o.sha256 == "" {
 		err := o.getHashes(ctx)
 		if err != nil {
-			return "", errors.Wrap(err, "failed to get hash")
+			return "", fmt.Errorf("failed to get hash: %w", err)
 		}
 	}
 	return *pHash, nil
@@ -971,7 +971,7 @@ func (o *Object) Size() int64 {
 // setMetaData sets the metadata from info
 func (o *Object) setMetaData(info *api.Item) (err error) {
 	if info.IsFolder {
-		return errors.Wrapf(fs.ErrorNotAFile, "%q is a folder", o.remote)
+		return fmt.Errorf("%q is a folder: %w", o.remote, fs.ErrorNotAFile)
 	}
 	o.hasMetaData = true
 	o.size = info.Size
@@ -1058,7 +1058,7 @@ func (o *Object) downloadURL(ctx context.Context) (URL string, err error) {
 		return "", err
 	}
 	if !result.IsValid() {
-		return "", errors.Errorf("fetched invalid link %+v", result)
+		return "", fmt.Errorf("fetched invalid link %+v", result)
 	}
 	o.link = &result
 	return o.link.URL(), nil
@@ -1146,7 +1146,7 @@ func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, op
 	if size == 0 {
 		formReader, contentType, overhead, err := rest.MultipartUpload(ctx, in, opts.Parameters, "content", leaf)
 		if err != nil {
-			return errors.Wrap(err, "failed to make multipart upload for 0 length file")
+			return fmt.Errorf("failed to make multipart upload for 0 length file: %w", err)
 		}
 
 		contentLength := overhead + size
@@ -1177,7 +1177,7 @@ func (o *Object) Update(ctx context.Context, in io.Reader, src fs.ObjectInfo, op
 		return err
 	}
 	if len(result.Items) != 1 {
-		return errors.Errorf("failed to upload %v - not sure why", o)
+		return fmt.Errorf("failed to upload %v - not sure why", o)
 	}
 	o.setHashes(&result.Checksums[0])
 	return o.setMetaData(&result.Items[0])