Add generic and krb5-specific name attributes

Roland needs this, and really, we've been needing this forever.

Status: builds.  No tests written yet.

NOTE: There are warnings that result from constification issues.
      We really need to s/\<const gss_/gss_const_/g.

Some warnings remain due to constification issues (there's too much
const gss_this or that instead of gss_const_this or that).
Some constification changes.