[krbdev.mit.edu #2587] Why does set_allowable_enctypes take a mechanism

[Kevin Coffman]

> Why does gss_krb5_set_allowable_enctypes take a mechanism oid?

Obviously, it is not used.  I just forgot to remove it.
I believe Love pointed this out as unnecessary earlier.

> O, for namespace consistency I've renamed
> krb5_gss_set_allowable_enctypes to gss_krb5_set_allowable_enctypes.

I'm happy with either name.  It makes our glue code a bit more
complicated.

BTW, I don't think we need to add any copyright.