DateTime.toTimeval

Stores the instant in time that datetime represents into tv.

The time contained in a #GTimeVal is always stored in the form of seconds elapsed since 1970-01-01 00:00:00 UTC, regardless of the time zone associated with datetime.

On systems where 'long' is 32bit (ie: all 32bit systems and all Windows systems), a #GTimeVal is incapable of storing the entire range of values that #GDateTime is capable of expressing. On those systems, this function returns false to indicate that the time is out of range.

On systems where 'long' is 64bit, this function never fails.