lavu/opt: allow to set sample and pixel format with av_opt_set_int()

This change requires the user to specify min and max value, and makes
possible to prevent the user to set AV_{SAMPLE,PIX}_FMT_NONE if
forbidden.

Add required ifdeffery in case of mixed libraries, when libavutil is
updated but not the other libraries.

This is a followup of 08d0969c1402ccec4dce44bd430128fb59d7b790.
