doc/examples/filtering_audio: make const arrays also static

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avdevice/dshow: make constant arrays static

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avdevice/vfwcap: make constant arrays static

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avfilter/graphparser: remove 256 char limit from create_filter()

Fixes Ticket2803

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>