expand_calls/calls.c change

[Richard Kenner]

    Was this patch bootstrapped?  It seems to have broken bootstrap for a
    lot of people.  The bug looks platform independent.

Yes, it was bootstrapped in a batch of about 7 other patches.  I'm not sure
why the warning didn't occur, but I suspect it's because it's *not*
platform-independent, though it sure looks like it should be.

Anyway, trivial enough to fix and I have done so.