fftools/ffmpeg: drop the 'h' key handling

This undocumented feature runtime-enables dumping input packets. I can
think of no reasonable real-world use case that cannot also be
accomplished in a different way. Keeping this functionality would
interfere with the following commit moving it to the input thread (then
setting the variable would require locking or atomics, which would be
unnecessarily complicated for a feature that probably nobody uses).

fftools/ffmpeg.c

@@ -3537,15 +3537,6 @@ static int check_keyboard_interaction(int64_t cur_time)
     if (key == '+') av_log_set_level(av_log_get_level()+10);
     if (key == '-') av_log_set_level(av_log_get_level()-10);
     if (key == 's') qp_hist     ^= 1;
-    if (key == 'h'){
-        if (do_hex_dump){
-            do_hex_dump = do_pkt_dump = 0;
-        } else if(do_pkt_dump){
-            do_hex_dump = 1;
-        } else
-            do_pkt_dump = 1;
-        av_log_set_level(AV_LOG_DEBUG);
-    }
     if (key == 'c' || key == 'C'){
         char buf[4096], target[64], command[256], arg[256] = {0};
         double time;