Add _android files for building DartVM on Android

runtime/bin/file_android.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 "bin/file.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/stat.h>
 #include <unistd.h>
@@ skipping 222 matching lines @@
   int result = fstat(fd, &buf);
   if (result == -1) {
     FATAL2("Failed stat on file descriptor %d: %s", fd, strerror(errno));
   }
   if (S_ISCHR(buf.st_mode)) return kTerminal;
   if (S_ISFIFO(buf.st_mode)) return kPipe;
   if (S_ISSOCK(buf.st_mode)) return kSocket;
   if (S_ISREG(buf.st_mode)) return kFile;
   return kOther;
 }