smbd: ensure we do a base open for internal stream deletes

smbd: ensure we do a base open for internal stream deletes

Otherwise we're not opening the basefile so fsp->base_fsp remains NULL for fsp
handles on streams. As there are some places that use the check (fsp->base_fsp
!= NULL) to check for stream handles, eg streams_xattr_fstat(), we must ensure
it is set otherwise we open a pretty big window for undefined behaviour.

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