shared: Add timespec_is_zero helper

Add a helper function to check if a struct timespec is zero. This helper
will be used in the upcoming commits to transition the Weston codebase
to struct timespec.

Signed-off-by: Alexandros Frantzis <alexandros.frantzis@collabora.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
2 files changed