Fix DexFile::GetChecksum to work on plain .dex files

Change-Id: I8947e0288378a1cc31fd8e60dad0bf25a76cfd1e
diff --git a/src/dex_file.cc b/src/dex_file.cc
index 7b031f2..850415e 100644
--- a/src/dex_file.cc
+++ b/src/dex_file.cc
@@ -74,7 +74,7 @@
     return true;
   }
   if (IsValidDexFilename(filename)) {
-    UniquePtr<const DexFile> dex_file(DexFile::OpenFile(filename, "", false));
+    UniquePtr<const DexFile> dex_file(DexFile::OpenFile(filename, filename, false));
     if (dex_file.get() == NULL) {
       return false;
     }