Make test encoder test driver less likely to leak on failure.
Make test encoder test driver less likely to leak on failure.

Individual tests still need to be updated.

Change-Id: Ic433d0f742e13560b136f136b72b2a9973970d78

webmproject/libvpx,ShiftMediaProject/libvpx,mwgoldsmith/libvpx,ShiftMediaProject/libvpx,mwgoldsmith/libvpx,mwgoldsmith/libvpx,mwgoldsmith/vpx,webmproject/libvpx,webmproject/libvpx,mwgoldsmith/libvpx,mwgoldsmith/libvpx,webmproject/libvpx,mwgoldsmith/vpx,Topopiccione/libvpx,Topopiccione/libvpx,mwgoldsmith/vpx,mwgoldsmith/vpx,mwgoldsmith/vpx,mwgoldsmith/vpx,ShiftMediaProject/libvpx,Topopiccione/libvpx,Topopiccione/libvpx,Topopiccione/libvpx,ShiftMediaProject/libvpx,mwgoldsmith/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,Topopiccione/libvpx,webmproject/libvpx