avfilter: add hqx filter (hq2x, hq3x, hq4x)

Partially fixes Ticket #3404 (xbr filter remaining)
Do not show libzvbi in the configure output if it was not enabled.

It is already shown in the list of external libraries if it was enabled.
Show duratiion for large asf files as written in the file header.

Fixes ticket #3428.