POSIX requires that SSIZE_MAX have the same type as ssize_t, but
on 32-bit, we were defining it as a long even though ssize_t
resolves to an int. It also requires that SSIZE_MAX be usable
via preprocessor #if, so we can't cheat and use a cast.
If this were newlib, I'd have had to hack _intsup.h to probe the
qualities of size_t (via gcc's __SIZE_TYPE__), similar to how we
already probe the qualities of int8_t and friends, then cross our
fingers that ssize_t happens to have the same rank (most systems
do, but POSIX permits a system where they differ such as size_t
being long while ssize_t is int). Unfortunately gcc gives us
neither __SSIZE_TYPE__ nor __SSIZE_MAX__. On the other hand, our
limits.h is specific to cygwin, so we can just shortcut to the
correct results rather than being generic to all possible ABI.
Signed-off-by: Eric Blake <eblake@redhat.com>
6795ef7d37