Add a corresponding constant for DEX_NOINDEX.

Change-Id: I3393e7f21e8a4a3c4ea37822393189f81d2a4453
diff --git a/src/raw_dex_file.h b/src/raw_dex_file.h
index 7e158e41..8363f1f 100644
--- a/src/raw_dex_file.h
+++ b/src/raw_dex_file.h
@@ -19,6 +19,9 @@
   static const byte kDexMagicVersion[];
   static const size_t kSha1DigestSize = 20;
 
+  // The value of an invalid index.
+  static const uint32_t kDexNoIndex = 0xFFFFFFFF;
+
   // Raw header_item.
   struct Header {
     uint8_t magic_[8];