mplayer2: Remove blacklist

mplayer2 no longer needs to be blacklisted as OE-core has moved
to libav_9.16.

[v2-v3] Also update build dependencies to quash QA warnings, using
PACKAGECONFIG for most optional features.

Signed-off-by: Gary Thomas <gary@mlbassoc.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>