Fix compatibility issues with the timespec struct

[github at samba.org]

New comment by douglasbagnall on Samba Github repository

https://github.com/samba-team/samba/pull/212#issuecomment-682196615
Comment:
@joankaradimov, Samba does not actually use github, and nothing will come of this if it is left here.

The ways to get this noticed are to use https://gitlab.com/samba-team/samba/ or send the patch to the samba-technical list.

(yes, we did try github for a short time and you walked right into that trap -- not you fault, sorry).