[audacity-freeworld/f24] (4 commits) ...Use bcond_without correctly, fix wx-config-3.0-gtk2 detection, also simplify

Summary of changes: a353858... Rebuilt for ffmpeg-3.1.1 (*) 0424cce... 2.1.3 Alpha git snapshot 2016-11-09. (*) 3e67739... fix mp3importexport conditional. (*) 77eb5e2... Use bcond_without correctly, fix wx-config-3.0-gtk2 detecti (*) (*) This commit already existed in another branch; no separate mail sent