vpx_scale_test: fix segfault on alloc failure
vpx_scale_test: fix segfault on alloc failure

check the return of ResetImage() before continuing

Change-Id: Iff0b038f7b9761113b8cf33a511a5306640d1273

webmproject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,ShiftMediaProject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx