Keep track of the sparse status of an open file handle. Allows bypass of

Keep track of the sparse status of an open file handle. Allows bypass of
strict allocation on sparse files. Files opened as POSIX opens are always
sparse.

Autobuild-User: Jeremy Allison <jra@samba.org>
Autobuild-Date: Tue Dec 21 04:12:22 CET 2010 on sn-devel-104