Move cfunction invocation code to the interpreter loop.

bytecode.h

@@ -42,7 +42,7 @@ const struct opcode_description* opcode_describe(opcode op);
 
 
 #define MAX_CFUNCTION_ARGS 10
-typedef void (*cfunction_ptr)(void);
+typedef void (*cfunction_ptr)();
 struct cfunction {
   cfunction_ptr fptr;
   const char* name;