Unquicken dex files before exporting from oatdump

Benefit from the vdex unquicken method when exporting dex files from
oatdump (--export-dex-to). Currently oatdump exports the quickened dex
files as generated by the dex compiler (dex-to-dex transformations).
With this commit the dex files associated with the input oat file are
unquickened before exporting.

In contrast to the other VdexFile::Unquicken() calls, in this case it
is useful to decompile a RETURN_VOID_NO_BARRIER into a RETURN_VOID. As
such, the required changes around the decompile_return_instruction flag
were made since it was hardcoded to false.

This feature is mostly useful when inspecting oat files that have the
original bytecode being stripped from the matching APK. If unquicken
is successful, the old checksum is expected to match.

Test: test-art-host

Change-Id: I9133d5f488ee3451c8f361ae90d1e12857529b1e
Signed-off-by: Anestis Bechtsoudis <anestis@census-labs.com>