New issue by znwulf on void-packages repository

https://github.com/void-linux/void-packages/issues/12486
Description: It appears OpenSSH is building without the '--with-kerberos5' flag rendering sshd unable to support Kerberos authentication. sshd fails config parsing tests raising 'unsupported option' errors and does not enable kerberos authentication support when restarted.

### System

* xuname:  Void 4.19.50_1 x86_64 GenuineIntel/KVM uptodate rFF
* package:  openssh 8.0p1 r2

### Expected behavior
Setting the following params in /etc/ssh/sshd_config:
```
# Kerberos options
KerberosAuthentication yes
KerberosOrLocalPasswd yes
KerberosTicketCleanup yes

# GSSAPI options
GSSAPIAuthentication yes
GSSAPICleanupCredentials yes
```

Should pass sshd's config parsing:
```
[root@kerberos-1]# sshd -t
[root@kerberos-1]#
```

### Actual behavior
sshd config test fails with unsupported options:
```
[root@kerberos-1]# sshd -T
/etc/ssh/sshd_config line 52: Unsupported option KerberosAuthentication
/etc/ssh/sshd_config line 53: Unsupported option KerberosOrLocalPasswd
/etc/ssh/sshd_config line 54: Unsupported option KerberosTicketCleanup
/etc/ssh/sshd_config line 58: Unsupported option GSSAPIAuthentication
/etc/ssh/sshd_config line 59: Unsupported option GSSAPICleanupCredentials
reprocess config line 52: Unsupported option KerberosAuthentication
reprocess config line 58: Unsupported option GSSAPIAuthentication
...
```

### Steps to reproduce the behavior
Enable the following params in /etc/ssh/sshd_config:
```
# Kerberos options
KerberosAuthentication yes
KerberosOrLocalPasswd yes
KerberosTicketCleanup yes

# GSSAPI options
GSSAPIAuthentication yes
GSSAPICleanupCredentials yes
```

Run the sshd config parse test:
```
[root@kerberos-1]# sshd -T
[root@kerberos-1]#
```