video: remove user-controllable PTS sorting (--pts-association-mode)

Useless. Sometimes it might be useful to make some extremely broken
files work, but on the other hand --no-correct-pts is sufficient for
these cases.

While we still need some of the code for AVI, the "auto" mode in
particular inflated the size of the code.

options/options.c

@@ -521,8 +521,6 @@ const m_option_t mp_opts[] = {
 
     // a-v sync stuff:
     OPT_FLAG("correct-pts", correct_pts, 0),
-    OPT_CHOICE("pts-association-mode", user_pts_assoc_mode, 0,
-               ({"auto", 0}, {"decoder", 1}, {"sort", 2})),
     OPT_FLAG("initial-audio-sync", initial_audio_sync, 0),
     OPT_CHOICE("video-sync", video_sync, 0,
                ({"audio", VS_DEFAULT},
@@ -754,7 +752,6 @@ const struct MPOpts mp_default_opts = {
     .edition_id = -1,
     .default_max_pts_correction = -1,
     .correct_pts = 1,
-    .user_pts_assoc_mode = 1,
     .initial_audio_sync = 1,
     .frame_dropping = 1,
     .term_osd = 2,

options/options.h

@@ -144,7 +144,6 @@ typedef struct MPOpts {
     int chapterrange[2];
     int edition_id;
     int correct_pts;
-    int user_pts_assoc_mode;
     int initial_audio_sync;
     int video_sync;
     double sync_max_video_change;