avcodec: remove obsolete FF_API_FAST_MALLOC cruft

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

libavcodec/avcodec.h

@@ -42,11 +42,6 @@
 
 #include "version.h"
 
-#if FF_API_FAST_MALLOC
-// to provide fast_*alloc
-#include "libavutil/mem.h"
-#endif
-
 /**
  * @defgroup libavc Encoding/Decoding Library
  * @{

libavcodec/version.h

@@ -132,9 +132,6 @@
 #ifndef FF_API_MAX_BFRAMES
 #define FF_API_MAX_BFRAMES       (LIBAVCODEC_VERSION_MAJOR < 57)
 #endif
-#ifndef FF_API_FAST_MALLOC
-#define FF_API_FAST_MALLOC       (LIBAVCODEC_VERSION_MAJOR < 56)
-#endif
 #ifndef FF_API_NEG_LINESIZES
 #define FF_API_NEG_LINESIZES     (LIBAVCODEC_VERSION_MAJOR < 57)
 #endif