Fixes for less common platforms

[nE0sIghT]

Hello!

Here are fixes for issues affecting less-common platforms found via Debian tests [1]

d4e0572 fixes incorrect C type handling on big-endian arches. Tested in an s390x vm.
9381d9f fixes buffer-size handling on 32-bit architectures. Tested in an i386 docker container on an amd64 host and in a powerpc vm
39b7ba5 fixes timeout handling on 32-bit big-endian powerpc. Tested in a powerpc vm.
d663292 relaxes test assumptions that caused failures on alpha and loong64. Tested in a loong64 vm. I hope it will work for alpha too.
ac16a6b fixes the SQPOLL fallback when io_uring_setup() is denied in restricted environments, as observed in Debian's amd64 autopkgtests [2].

The last issue can be reproduced with:

strace -f -qq -o /dev/null \
    -e trace=io_uring_setup \
    --inject=io_uring_setup:error=EACCES:when=3 \
    dpkg-buildpackage # (or pytest...)

[1] https://buildd.debian.org/status/package.php?p=caio
[2] https://ci.debian.net/packages/c/caio/testing/amd64/74855165/