Is pacal calling convention supported?

This is related to #485. The Win16 API function calls should use __pascal calling convention for the argument order to be right (left to right). I didn't find anything useful in the code regarding this issue. Is it possible to define a new convention with arguments being pushed left to right? Maybe there's a parameter for a cspec definition that reverses the argument order? So far I couldn't find an easy way to do that.