s3: smbd: Fix *allocate* calls to follow POSIX error return convention.

s3: smbd: Fix *allocate* calls to follow POSIX error return convention.

vfswrap_fallocate() is broken in that it can call posix_fallocate()
which returns an int error (and doesn't set errno) but can also
call Linux fallocate() which returns -1 and sets errno.

Standardize on the -1,errno convention.

Reported by Jones <jones.kstw@gmail.com> who provided the
initial patch. This patch tested and confirmed working
by him as well.

https://bugzilla.samba.org/show_bug.cgi?id=10982

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: David Disseldorp <ddiss@suse.de>