Fix bug in OatFileAssistant::GetBestOatFile.

Previously, GetBestOatFile would fail to return an oat file in the
case where a non-executable oat file was requested and the only
problem with the oat file was that it wasn't relocated.

Bug: 22561444
Change-Id: I6446bf474afaf6c97861e7a89bd74a07c5a52a21
3 files changed