Log message:
sys/fs/smbfs/smbfs_smb.c			1.41
sys/fs/smbfs/smbfs_subr.h			1.20

Add support for 64 bit file offsets to smbfs_smb_setfsize(), largely
based on code taken from FreeBSD.

This stops truncation of files larger than 4GB by VOP_SETATTR() which e.g.
happened when copying large files "rump_smbfs". Kudos to Antti Kantee
for diagnosing the problem in smbfs_smb_setfsize().
[tron, ticket #4711]