Move utils.h and utils.cc from runtime/vm to runtime/platform

runtime/vm/disassembler_x64.cc

 // Copyright (c) 2012, 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 "vm/disassembler.h"
 
 #if !defined(_WIN32)  // Disassembler is not yet supported under WIN32.
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 #endif
 
-#include "platform/assert.h"
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
+#include "platform/assert.h"
 
 namespace dart {
 
 void Disassembler::Disassemble(uword start,
                                uword end,
                                DisassemblyFormatter* formatter) {
   // First print the actual addresses so that we know where in memory this is
   // being disassembled from.
   formatter->Print("start: %p  end: %p\n", start, end);
 
@@ skipping 74 matching lines @@
 int Disassembler::DecodeInstruction(char* hexa_buffer, intptr_t hexa_size,
                                     char* human_buffer, intptr_t human_size,
                                     uword pc) {
   UNIMPLEMENTED();
   return 0;
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64