posix.RenameFile(): Allow overwriting an empty directory (#5551)
posix.RenameFile(): Allow overwriting an empty directory (#5551)

Overwriting files is allowed, but since the introduction of
the object directory, we will aslo need to allow overwriting
an empty directory. Putting twice the same object directory
won't fail with 403 error anymore.
aead/minio,fwessels/minio,aead/minio,rushenn/minio,aead/minio,jimjag/minio,minio/minio,NitishT/minio,abperiasamy/minio,fwessels/minio,harshavardhana/minio,minio/minio,aead/minio,NitishT/minio,vadmeste/minio,jimjag/minio,harshavardhana/minio,krisis/minio,jimjag/minio,harshavardhana/minio,balamurugana/minio,rushenn/minio,jimjag/minio,aead/minio,krisis/minio,NitishT/minio,fwessels/minio,harshavardhana/minio,aead/minio,harshavardhana/minio,vadmeste/minio,rushenn/minio,aead/minio,krishnasrinivas/minio,abperiasamy/minio,harshavardhana/minio,aead/minio,abperiasamy/minio,fwessels/minio,harshavardhana/minio,krishnasrinivas/minio,balamurugana/minio,donatello/minio,krishnasrinivas/minio,krishnasrinivas/minio,abperiasamy/minio,NitishT/minio,donatello/minio,rushenn/minio,harshavardhana/minio