avformat/avlanguage: Remove long disabled av_convert_lang_to

1582e306a4 scheduled it for removal with
libavformat major version 58, but it was never removed.

Reviewed-by: Paul B Mahol <onemda@gmail.com
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavformat/avlanguage.c

@@ -763,10 +763,3 @@ const char *ff_convert_lang_to(const char *lang, enum AVLangCodespace target_cod
 
     return NULL;
 }
-
-#if LIBAVFORMAT_VERSION_MAJOR < 58
-const char *av_convert_lang_to(const char *lang, enum AVLangCodespace target_codespace)
-{
-    return ff_convert_lang_to(lang, target_codespace);
-}
-#endif

libavformat/avlanguage.h

@@ -21,9 +21,6 @@
 #ifndef AVFORMAT_AVLANGUAGE_H
 #define AVFORMAT_AVLANGUAGE_H
 
-#include "libavutil/attributes.h"
-#include "libavformat/version.h"
-
 /**
  * Known language codespaces
  */
@@ -38,9 +35,5 @@ enum AVLangCodespace {
  * @return NULL if the provided lang is null or invalid.
  */
 const char *ff_convert_lang_to(const char *lang, enum AVLangCodespace target_codespace);
-#if LIBAVFORMAT_VERSION_MAJOR < 58
-attribute_deprecated
-const char *av_convert_lang_to(const char *lang, enum AVLangCodespace target_codespace);
-#endif
 
 #endif /* AVFORMAT_AVLANGUAGE_H */