Change the type of newsize argument in the smbfs_smb_setfsize() function
from int to int64.
MSDN says that SMB_SET_FILE_END_OF_FILE_INFO uses signed 64-bit integer
to specify offset, but since smbfs_smb_setfsize() has used plain int,
a value was truncated in case when offset was larger than 2G.
	https://msdn.microsoft.com/en-us/library/ff469975.aspx

In particular, now `truncate -s 10G` will work correctly on the mounted
SMB share.