Revamp vdex format for better extensibility.

- Remove class loader context and boot classpath checksum sections.
  Those are not needed now that VerifierDeps don't depend on them.
- Remove remaining quickening encoding.
- Introduce sections in a vdex file, which can be extended without
  requiring a version change.

Test: test.py
Bug: 160294863

Change-Id: I4e3e25f34d242dc4de37f30ba9d78bcffbc1436d
diff --git a/dex2oat/dex2oat_vdex_test.cc b/dex2oat/dex2oat_vdex_test.cc
index fd51108..d9a555a 100644
--- a/dex2oat/dex2oat_vdex_test.cc
+++ b/dex2oat/dex2oat_vdex_test.cc
@@ -81,7 +81,7 @@
     }
 
     // Verify the deps.
-    VdexFile::VerifierDepsHeader vdex_header = vdex->GetVerifierDepsHeader();
+    VdexFile::VdexFileHeader vdex_header = vdex->GetVdexFileHeader();
     if (!vdex_header.IsValid()) {
       ::testing::AssertionFailure() << "Invalid vdex header";
     }