Fix error code when smbclient puts a file over an existing directory

Fix error code when smbclient puts a file over an existing directory

Windows returns NT_STATUS_FILE_IS_A_DIRECTORY, as does Samba 3.0. 3.2 and
following returned NT_STATUS_INVALID_PARAMETER which is wrong.

Before I converted reply_open_and_X to create_file() we called
open_file_ntcreate directly. Passing through open&X for a filename that exists
as a directory ends up in open_directory after having tried open_file_ntcreate.
Some check in there returns NT_STATUS_INVALID_PARAMETER. With this additional
FILE_NON_DIRECTORY_FILE flag we get the correct error message back from
create_file_unixpath before trying open_directory().

Survives make test, but as this also touches the other open variants I would
like others to review this.

Volker