Rename num_show_frames by num_coding_frames
Rename num_show_frames by num_coding_frames

Change-Id: I2acc7d6bde2ec2fae4460869663db1e8f6c576fe

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