krb5: Improve cccol sub naming; add gss_store_cred_into2()

- Formalize the TYPE:collection_name:subsidiary_name naming scheme for
   ccaches in ccache collections
    - KEYRING: ccaches are weird because they have one more optional field: the
      "anchor", so rather than just assume a naming convention everywhere, we
      add new functions as well
 - Add krb5_cc_{resolve,default}_sub() that allows one to specify a
   "subsidiary" ccache name in a collection separately from the
   collection name
 - Add krb5_cc_{resolve,default}_for() which take a principal name,
   unparse it, and use it as the subsidiary ccache name (with colons
   replaced)
 - Make kinit use the new interfaces
 - Add missing DIR ccache iteration functionality
 - Revamps test_cc
 - Add krb5_cc_get_collection() and krb5_cc_get_subsidiary()
 - Bump the ccops SPI version number
 - Add gss_store_cred_into2()
 - Make MEMORY:anonymous not linked into the global MEMORY ccache
   collection, and uses this for delegated cred handles

TBD:

 - Split this up into a krb5 change and gss mech_krb5 change?
 - Add krb5_cc_init_and_store() utility, per Greg's suggestion?

lib/gssapi/gssapi_mech.h

@@ -474,6 +474,17 @@ _gss_store_cred_into_t(OM_uint32 *minor_status,
 		       gss_OID_set *elements_stored,
 		       gss_cred_usage_t *cred_usage_stored);
 
+typedef OM_uint32 GSSAPI_CALLCONV
+_gss_store_cred_into2_t(OM_uint32 *minor_status,
+		        gss_const_cred_id_t input_cred_handle,
+		        gss_cred_usage_t input_usage,
+		        gss_OID desired_mech,
+		        OM_uint32 store_cred_flags,
+		        gss_const_key_value_set_t cred_store,
+		        gss_OID_set *elements_stored,
+		        gss_cred_usage_t *cred_usage_stored,
+                        gss_buffer_set_t *env);
+
 typedef OM_uint32 GSSAPI_CALLCONV
 _gss_set_neg_mechs_t(OM_uint32 *minor_status,
 		     gss_cred_id_t cred_handle,
@@ -623,6 +634,7 @@ typedef struct gssapi_mech_interface_desc {
 	_gss_query_mechanism_info_t	*gm_query_mechanism_info;
 	_gss_query_meta_data_t		*gm_query_meta_data;
 	_gss_exchange_meta_data_t	*gm_exchange_meta_data;
+	_gss_store_cred_into2_t		*gm_store_cred_into2;
         struct gss_mech_compat_desc_struct  *gm_compat;
 } gssapi_mech_interface_desc, *gssapi_mech_interface;