Functions with varargs support

We need varargs support, since almost any simple tutorial use `printf`. Without that support we cannot go to public probably, otherwise Cesium always look as toy project.

Look for the number `196` in the code to find clues to implement this feature.

Search the codebase for the number 196, as the issue suggests, and trace the related compiler paths before deciding the scope of varargs support. The work is done when C functions accepting variable arguments can support common uses such as printf and the relevant compiler behavior is covered by the project’s existing validation.

Written by the indexing model from the issue text.