avcodec/version: delay removial of FF_API_AUDIO_CONVERT/FF_API_AVCODEC_RESAMPLE

Some applications still use this deprecated API
Its not nice to remove it when its still in use and as long as it doesnt
cause us any work to keep it.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/version.h

@@ -64,7 +64,7 @@
 #define FF_API_CODEC_ID          (LIBAVCODEC_VERSION_MAJOR < 57)
 #endif
 #ifndef FF_API_AUDIO_CONVERT
-#define FF_API_AUDIO_CONVERT     (LIBAVCODEC_VERSION_MAJOR < 56)
+#define FF_API_AUDIO_CONVERT     (LIBAVCODEC_VERSION_MAJOR < 57)
 #endif
 #ifndef FF_API_AVCODEC_RESAMPLE
 #define FF_API_AVCODEC_RESAMPLE  FF_API_AUDIO_CONVERT