Change legacy vp8/9_write_yuv_frame to vpx_write_yuv_files.
Delete some flags that can be enabled during build.

To enable writing denoised YUV, use the following command line:
CFLAGS='-DOUTPUT_YUV_DENOISED' ./configure
--enable-vp9-temporal-denoising

For skinmap, use CFLAGS='-DOUTPUT_YUV_SKINMAP'

Change-Id: I236974ac8b3cf279d20c4dc7f6162d8b480b6528