This parameter was incorrectly declared to be a pointer to a function
accepting zero parameters. The intent of makecontext is that it is
possible to pass integer parameters to the function, so this should
have been a pointer to a function accepting an unspecified set of
parameters.
struct __ucontext;
int getcontext(struct __ucontext *);
-void makecontext(struct __ucontext *, void (*)(void), int, ...);
+void makecontext(struct __ucontext *, void (*)(), int, ...);
int setcontext(const struct __ucontext *);
int swapcontext(struct __ucontext *, const struct __ucontext *);