Fix Windows build by removing bad include.

runtime/vm/simulator_arm.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include <math.h>  // for isnan.
 #include <setjmp.h>
 #include <stdlib.h>
-#include <pthread.h>
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_ARM)
 
 // Only build the simulator if not compiling for real ARM hardware.
 #if !defined(HOST_ARCH_ARM)
 
 #include "vm/simulator.h"
 
 #include "vm/assembler.h"
@@ skipping 2712 matching lines @@
   // isolate->ChangeStateToGeneratedCode();
   set_register(kExceptionObjectReg, bit_cast<int32_t>(object.raw()));
   buf->Longjmp();
 }
 
 }  // namespace dart
 
 #endif  // !defined(HOST_ARCH_ARM)
 
 #endif  // defined TARGET_ARCH_ARM