fic: Support rendering cursors

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
avutil: Add av_get_time_base_q()

This fixes usage of AV_TIME_BASE_Q in C++ applications, which
cannot use compound literals directly in their code.

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>