selftest: run vfs.fruit test against a share that deletes empty resource forks

selftest: run vfs.fruit test against a share that deletes empty resource forks

This reveals a bug in the AppleDouble conversion code: the conversion code that
unlinks an empty resource fork AppleDouble sidecar file ("._file") gets
triggered as part of open_file_ntcreate(..., "file:AFP_AfpResource", ...):

after SMB_VFS_OPEN() has been called with O_CREAT, what created the file, we
call SMB_VFS_FSTAT() on the just created filehandle. This ends up in
ad_convert(), finds the resource fork empty and thus deletes the file.

Bug: https://bugzilla.samba.org/show_bug.cgi?id=13958

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