Remove the Kerberos portability header

Summary: It's no longer needed.

Reviewed By: yfeldblum

Differential Revision: D9847073

fbshipit-source-id: 072f4e5fc207ab199689e42c4f492d4fcb67aa8e

folly/portability/Krb5.h

-/*
- * Copyright 2016-present Facebook, Inc.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *   http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#pragma once
-
-// Bring in MAXPATHLEN so kerberos doesn't make up its
-// own defintion of it.
-#include <folly/portability/Stdlib.h>
-
-#include <folly/portability/Windows.h>
-
-#include <gssapi/gssapi_generic.h>
-#include <gssapi/gssapi_krb5.h>
-#include <krb5/krb5.h>
-
-// Kerberos defines a bunch of things that we implement as actual
-// functions, so undefine whatever mess kerberos has done.
-#undef strcasecmp
-#undef strncasecmp
-#undef strdup
-#undef strtok_r