lavc: Drop deprecated av_fast_malloc() compatibility

Deprecated in 10/2013.

libavcodec/avcodec.h

@@ -41,11 +41,6 @@
 
 #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

@@ -47,9 +47,6 @@
  * the public API and may change, break or disappear at any time.
  */
 
-#ifndef FF_API_FAST_MALLOC
-#define FF_API_FAST_MALLOC       (LIBAVCODEC_VERSION_MAJOR < 58)
-#endif
 #ifndef FF_API_EMU_EDGE
 #define FF_API_EMU_EDGE          (LIBAVCODEC_VERSION_MAJOR < 58)
 #endif