lavc: remove disabled FF_API_LIBMPEG2 cruft

libavcodec/avcodec.h

@@ -2377,9 +2377,6 @@ typedef struct AVCodecContext {
 #define FF_IDCT_INT           1
 #define FF_IDCT_SIMPLE        2
 #define FF_IDCT_SIMPLEMMX     3
-#if FF_API_LIBMPEG2
-#define FF_IDCT_LIBMPEG2MMX   4
-#endif
 #if FF_API_MMI
 #define FF_IDCT_MMI           5
 #endif

libavcodec/version.h

@@ -49,9 +49,6 @@
 #ifndef FF_API_REQUEST_CHANNELS
 #define FF_API_REQUEST_CHANNELS (LIBAVCODEC_VERSION_MAJOR < 56)
 #endif
-#ifndef FF_API_LIBMPEG2
-#define FF_API_LIBMPEG2          (LIBAVCODEC_VERSION_MAJOR < 55)
-#endif
 #ifndef FF_API_MMI
 #define FF_API_MMI               (LIBAVCODEC_VERSION_MAJOR < 55)
 #endif