Port to Debian Buster and OpenAFS 1.8
libopenafs-dev links against heimdal instead of krb5 now, update
Makefile to link against that.
MAXPATHLEN is no longer defined, use POSIX PATH_MAX instead.
- [DBH] Makefile
- [DBH] debian/changelog
- [DBH] debian/control
- [DBH] nss_afs.c