target regtest-lavfi_pix_fmts.

The lavfi_pix_fmts test is disabled, this because there are
many tests which are failing, and there are still some output files
which cannot be played by NUT/ffplay.

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@23297 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b