[MLton] interrupted system call

[Henry Cejtin]

Sorry, I haven't been following everything here.  Is the `Signal.restart' flag
a notion of being able to specify if we want signals to have the SA_RESTART
flag either on or off?  If so then I guess it is sufficient, but very very
counter-intuitive and not what you see in C.  The point is that in C I expect
my handler to run quite soon after the signal arrives.  If the handler decides
to call exit(), then the system call is not going to continue (same for
longjmp()).
I should probably re-read `The Rise of "Wirse is Better"' by Gabriel to
remember what he says about the `PC loser-ing' problem, which is all about
system calls returning EINTR in Unix.