avformat/avformat: remove dead code

Signed-off-by: James Almer <jamrial@gmail.com>

libavformat/avformat.h

@@ -478,12 +478,7 @@ typedef struct AVProbeData {
 #define AVFMT_NOGENSEARCH   0x4000 /**< Format does not allow to fall back on generic search */
 #define AVFMT_NO_BYTE_SEEK  0x8000 /**< Format does not allow seeking by bytes */
 #define AVFMT_ALLOW_FLUSH  0x10000 /**< Format allows flushing. If not set, the muxer will not receive a NULL packet in the write_packet function. */
-#if LIBAVFORMAT_VERSION_MAJOR <= 54
-#define AVFMT_TS_NONSTRICT 0x8020000 //we try to be compatible to the ABIs of ffmpeg and major forks
-#else
-#define AVFMT_TS_NONSTRICT 0x20000
-#endif
-                                   /**< Format does not require strictly
+#define AVFMT_TS_NONSTRICT 0x20000 /**< Format does not require strictly
                                         increasing timestamps, but they must
                                         still be monotonic */
 #define AVFMT_TS_NEGATIVE  0x40000 /**< Format allows muxing negative