edje_calc: Exception handling if no calculation is required.

If there is no object swllowed, do not run part_calc on it.
This swallow will be calculated if there is an associated part, otherwise it will not need to be calculated.

When the app is launched, a lot of edje calculation logic is executed.
Most of the edje size is missing, so the calculation result is meaningless.
Added code to prevent this.

Reviewed-by: Cedric BAIL <cedric.bail@free.fr>
Differential Revision: https://phab.enlightenment.org/D10605