This reverts commit b7168586.

The commit lead to the use of an uninitialized variable.
Other issues were listed by Andreas Rheinhardt:
https://ffmpeg.org/pipermail/ffmpeg-devel/2020-March/259150.html

(cherry picked from commit 8b1f07ef)

In addition, it is not understandable why the patch that neither
claims to fix a regression nor a security issue was backported.