[libc] Remove unneeded extra include

libc/src/time/mktime.h

 //===-- Implementation header of mktime -------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_LIBC_SRC_TIME_MKTIME_H
 #define LLVM_LIBC_SRC_TIME_MKTIME_H
 
-#include "src/time/mktime.h"
 #include <time.h>
 
 namespace __llvm_libc {
 
 time_t mktime(struct tm *t1);
 
 } // namespace __llvm_libc
 
 #endif // LLVM_LIBC_SRC_TIME_MKTIME_H
 
 #include "include/time.h"