Generalize MSLSA ccache type to a plug-in based ccache type

lib/krb5/context.c

@@ -247,9 +247,7 @@ cc_ops_register(krb5_context context)
 #endif
     krb5_cc_register(context, &krb5_kcm_ops, TRUE);
 #endif
-#ifdef HAVE_MSLSA_CACHE
-    _krb5_mslsa_register_cc_ops(context, TRUE);
-#endif
+    _krb5_load_ccache_plugins(context);
     return 0;
 }