Are FFI calls interruptible?

[Edward Z. Yang]

Excerpts from Bas van Dijk's message of Sun Apr 24 16:10:46 -0400 2011:
> Well the whole block of code is under a mask_ so if FFI calls are not
> interruptible the queued up exceptions should not be fired.

Ah, I didn't know that.  I think it would be extremely surprising
for users if FFI calls ever grew the semanticcs that they unmasked
exceptions, so I don't think you have to worry too much about it.

This also makes me wonder if "interruptible" in the sense that we're
using it for FFI coincides with the sense of "interruptible" as used
by mask.  I suspect it might not (that is, a mask will still prevent
interruptible FFI calls from receiving interrupts.)  I will have to
investigate this.

Cheers,
Edward