Fix clean-unix rule for gssapi_krb5.h

Don't delete gssapi_krb5.h now that it is not generated.

[ghudson@mit.edu: also remove from generate-files-mac rule and from
.gitignore]
Update iprop_master_ulogsize documentation

When we removed the maximum number of ulog entries (#7368), we did not
update the documentation for that parameter in kdc.conf.  Reported by
Richard Basch.

ticket: 7849
target_version: 1.12.2
tags: pullup