Add _android files for building DartVM on Android

runtime/vm/gdbjit_android.h

Index: runtime/vm/gdbjit_android.h
diff --git a/runtime/vm/gdbjit_linux.h b/runtime/vm/gdbjit_android.h
similarity index 64%
copy from runtime/vm/gdbjit_linux.h
copy to runtime/vm/gdbjit_android.h
index 4d8d369f968132e8948ec54a29fb23f4a6ad7f7f..82c7070c36a669b15a83b0e14c122ec212573dc9 100644
--- a/runtime/vm/gdbjit_linux.h
+++ b/runtime/vm/gdbjit_android.h
@@ -1,13 +1,13 @@
-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// 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.
 
-#ifndef VM_GDBJIT_LINUX_H_
-#define VM_GDBJIT_LINUX_H_
+#ifndef VM_GDBJIT_ANDROID_H_
+#define VM_GDBJIT_ANDROID_H_
 
 extern "C" {
   void addDynamicSection(const char* symfile_addr, uint64_t symfile_size);
   void deleteDynamicSections();
 };
 
-#endif  // VM_GDBJIT_LINUX_H_
+#endif  // VM_GDBJIT_ANDROID_H_