fftools/cmdutils: drop prototypes for nonexistent functions

fftools/cmdutils.h

@@ -66,11 +66,6 @@ void exit_program(int ret) av_noreturn;
  */
 void init_dynload(void);
 
-/**
- * Initialize the cmdutils option system, in particular
- * allocate the *_opts contexts.
- */
-void init_opts(void);
 /**
  * Uninitialize the cmdutils option system, in particular
  * free the *_opts contexts and their contents.
@@ -108,8 +103,6 @@ int opt_report(void *optctx, const char *opt, const char *arg);
 
 int opt_max_alloc(void *optctx, const char *opt, const char *arg);
 
-int opt_codec_debug(void *optctx, const char *opt, const char *arg);
-
 /**
  * Limit the execution time.
  */