smbd: reuse smb_fname->fsp in create_file_default()

smbd: reuse smb_fname->fsp in create_file_default()

This is the big bang for the internal pathref fsps: up to this point the pathref
fsps were lingering around unused inside smb_fname->fsp.

With this change, the internal fsp will be the one that is going to be returned
from SMB_VFS_CREATE_FILE() if the client requested access mask matches the
criteria in open_file():

	uint32_t need_fd_mask =
		FILE_READ_DATA |
		FILE_WRITE_DATA |
		FILE_APPEND_DATA |
		FILE_EXECUTE |
		WRITE_DAC_ACCESS |
		WRITE_OWNER_ACCESS |
		SEC_FLAG_SYSTEM_SECURITY |
		READ_CONTROL_ACCESS;

As long as the client doesn't request any of the access rights listed above, we
reuse the smb_fname->fsp, otherwise we close the smb_fname->fsp and call
fd_open() to open a new fsp.

In the future we can remove the four non-IO related access rights from the list:

		WRITE_DAC_ACCESS |
		WRITE_OWNER_ACCESS |
		SEC_FLAG_SYSTEM_SECURITY |
		READ_CONTROL_ACCESS

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>