Use compute_arf_boost() in define_gf_group()
Use compute_arf_boost() in define_gf_group()

Remove reset_fpf_position() because
compute_arf_boost does not count on twopass->stats_in

Change-Id: I560dccfcc4a2cbaa8e78a493a070a416465db4a9

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