src.opts.mk: Do not allow WITHOUT_GSSAPI with MIT Kerberos

[ivy]

Summary

With MIT krb5, there is no libgssapi at all, and libgssapi_krb5 is
a mandatory component of krb5. Specifying WITHOUT_GSSAPI in this
case doesn't make sense, so raise an error.

Once Heimdal is removed from the tree, we can remove WITHOUT_GSSAPI
entirely.

[des]

This won't work. The correct solution is to register GSSAPI as a dependent of MITKRB5.

You must also regenerate src.conf.5 and include it in your commit:

cd tools/build/options
sh makeman >../../../share/man/man5/src.conf.5

[ivy]

In D51853#1184714, @des wrote:

This won't work. The correct solution is to register GSSAPI as a dependent of MITKRB5.

if you mean adding it to the previous .for list, i'm not sure this is right: we should raise an error if the user tries to set WITHOUT_GSSAPI because it doesn't make sense to do that; silently accepting it will be confusing.

this did work when i tested it. could you elaborate on why it won't work?

[des]

In D51853#1184725, @ivy wrote:

In D51853#1184714, @des wrote:

This won't work. The correct solution is to register GSSAPI as a dependent of MITKRB5.

if you mean adding it to the previous .for list, i'm not sure this is right: we should raise an error if the user tries to set WITHOUT_GSSAPI because it doesn't make sense to do that; silently accepting it will be confusing.

There are other option combinations that don't make sense either. We don't error out for any of them, we just silently fix them.

this did work when i tested it. could you elaborate on why it won't work?

It breaks makeman.

[ivy]

closing in favour of D51859 which is a better fix