Remove unused variables

[ghudson@mit.edu: squashed with similar commits]
Fix invalid test strings in t_oid.c

A missing comma caused two invalid strings to be concatenated.  The
resulting string was still invalid so the tests passed.

[ghudson@mit.edu: clarified commit message]
Fix error handling in k5_expand_path_tokens_extra

If strdup fails when copying extra tokens, we must terminate the
argument traversal before returning.

[ghudson@mit.edu: clarified commit message]
Fix argment validation in krb5_make_fulladdr

Check kaddr and kport, not kport twice.

[ghudson@mit.edu: clarified commit message, minor style change]
Avoid closing fd -1 in libkrad

If a krad_remote is released before its fd is set, we could close the
file descriptor -1, which is harmless but incorrect.  Check the fd in
remote_disconnect to avoid this.

[ghudson@mit.edu: clarified commit message, minor style change]
Fix error check in krb5_ldap_parse_principal_name

Test the correct variable for NULL to detect a strdup failure.

[ghudson@mit.edu: clarified commit message]