Handle varargs functions, specifically printf and scanf and friends

[artemdinaburg]

Right now varargs functions are detected as varargs, but we only emit the formal but not variable parameters.

As an example, we see:

unsigned int printf(unsigned char *arg0, ...);
...
unsigned int val6 = printf(data_4007c1);

Lets handle varargs functions better. For now, it is fine if it just hits *printf and *scanf and handles static strings. This may be some kind of specific pass or set of heuristics, as long as it is identified as such and not comingled with other code.