Without looking at your code too carfully, I notice that you're trying to do something after the return in your C function. Inline_Stack_Void won't be called; could this be causing your segfault?
Take a look at the Inline C Cookbook section on variable argument lists. The link above should take you to the correct anchor. You're going to have undefined behavior if you use Inline_Stack_Vars in functions that don't have variable length arg lists.