ff_ffplay: merge 631ac655c00e978e19d05dab572bc1ffd6078c63

ffplay: implement separete audio decoder thread
ff_ffplay: merge cc4741888d7fa74074a295158fcbb88475a08a88

ffplay: fix indentation after last commit
ff_ffplay: merge 7ba727777587c1a83fb1f54bde5f960376e90dca
ff_ffplay: merge e971eef8c0d2ebe461bb17f19a590b53511cc8f2

Set -scan_all_pmts 1 in ffmpeg, ffplay and ffprobe if not set by user.

Fixes ticket #3762.
ff_ffplay: merge eaf4ab9802d5ad82a707514cae165c6db9e7bfc8

ffplay: signal the frame queue before closing audio

Fixed regression caused by 631ac655c00e978e19d05dab572bc1ffd6078c63 when ffplay
does not quit if the audio thread is blocked.