bdiff: use ssize_t in favor of Py_ssize_t in cpython-unaware locations
This function and struct will be exposed via cffi, so we need to
remove the cpython API dependency they currently have.
fixbundle() {
grep -v 'saving bundle' | grep -v 'saved backup' | \
grep -v added | grep -v adding | \
grep -v "unable to find 'e' for patching" | \
grep -v "e: No such file or directory" | \
cat
}