Fix an issue where MinIO was logging every error twice (#8953)

The logging subsystem was initialized under init() method in
both gateway-main.go and server-main.go which are part of
same package. This created two logging targets and hence
errors were logged twice. This PR moves the init() method
to common-main.go

cmd/common-main.go

@@ -17,7 +17,9 @@
 package cmd
 
 import (
+	"context"
 	"crypto/x509"
+	"encoding/gob"
 	"errors"
 	"net"
 	"path/filepath"
@@ -34,6 +36,17 @@ import (
 	"github.com/minio/minio/pkg/env"
 )
 
+func init() {
+	logger.Init(GOPATH, GOROOT)
+	logger.RegisterError(config.FmtError)
+
+	// Initialize globalConsoleSys system
+	globalConsoleSys = NewConsoleLogger(context.Background())
+	logger.AddTarget(globalConsoleSys)
+
+	gob.Register(StorageErr(""))
+}
+
 func verifyObjectLayerFeatures(name string, objAPI ObjectLayer) {
 	if (globalAutoEncryption || GlobalKMS != nil) && !objAPI.IsEncryptionSupported() {
 		logger.Fatal(errInvalidArgument,