lavfi/hue: use lookup tables

Signed-off-by: Paul B Mahol <onemda@gmail.com>
lavf/tee: add special select option
doc/muxers: add elaborated example for the tee muxer

The example shows how to combine bsfs and select options.
configure: Add exif to CONFIG_EXTRA.

Add exif as a common component in CONFIG_EXTRA in order to avoid many
dependencies to 'exif.o tiff_common.o' in lavc/Makefile.