So in this case we mostly need to include an internal header
(epiphany-syscalls.h). In a few cases an explicit prototype is added. We've
also got a return with no value in a function with a non-void return type.
Finally the asm_syscall interface expects a pointer as its first argument. In
a few cases we've actually got an int (file descriptor) which we just cast to a
void *.
It's slightly more than Jeff J's pre-approval, but I think still reasonable.
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