Add flock(2)ing on dex-cache files to prevent races

Bug: 9071417
Change-Id: I1ee9ff281867f90fba7a8ed8bbf06b33ac29d511
diff --git a/compiler/elf_writer_test.cc b/compiler/elf_writer_test.cc
index e48806e..ffe1f72 100644
--- a/compiler/elf_writer_test.cc
+++ b/compiler/elf_writer_test.cc
@@ -62,7 +62,7 @@
 
   ASSERT_EQ(0, dlclose(dl_oat_so));
 
-  UniquePtr<File> file(OS::OpenFile(elf_filename.c_str(), false));
+  UniquePtr<File> file(OS::OpenFileForReading(elf_filename.c_str()));
   ASSERT_TRUE(file.get() != NULL);
   {
     UniquePtr<ElfFile> ef(ElfFile::Open(file.get(), false, false));