Remove unused functions

[kevinschweikert]

I saw some warnings on my machine because FFmpeg 7.1 deprecated codec->pix_fmts (see https://github.com/FFmpeg/FFmpeg/blob/master/doc/APIchanges#L60)

c_src/xav/utils.c:7:14: warning: 'pix_fmts' is deprecated [-Wdeprecated-declarations]
    7 |   if (codec->pix_fmts == NULL) {
      |              ^
/opt/homebrew/Cellar/ffmpeg/7.1/include/libavcodec/codec.h:214:5: note: 'pix_fmts' has been explicitly marked deprecated here
  214 |     attribute_deprecated
      |     ^
/opt/homebrew/Cellar/ffmpeg/7.1/include/libavutil/attributes.h:100:49: note: expanded from macro 'attribute_deprecated'
  100 | #    define attribute_deprecated __attribute__((deprecated))
      |                                                 ^
c_src/xav/utils.c:10:28: warning: 'pix_fmts' is deprecated [-Wdeprecated-declarations]
   10 |     for (int i = 0; codec->pix_fmts[i] != -1; i++) {
      |                            ^
/opt/homebrew/Cellar/ffmpeg/7.1/include/libavcodec/codec.h:214:5: note: 'pix_fmts' has been explicitly marked deprecated here
  214 |     attribute_deprecated
      |     ^
/opt/homebrew/Cellar/ffmpeg/7.1/include/libavutil/attributes.h:100:49: note: expanded from macro 'attribute_deprecated'
  100 | #    define attribute_deprecated __attribute__((deprecated))
      |                                                 ^
c_src/xav/utils.c:11:43: warning: 'pix_fmts' is deprecated [-Wdeprecated-declarations]
   11 |       fprintf(stdout, "fmt: %d\n", codec->pix_fmts[i]);
      |                                           ^
/opt/homebrew/Cellar/ffmpeg/7.1/include/libavcodec/codec.h:214:5: note: 'pix_fmts' has been explicitly marked deprecated here
  214 |     attribute_deprecated
      |     ^
/opt/homebrew/Cellar/ffmpeg/7.1/include/libavutil/attributes.h:100:49: note: expanded from macro 'attribute_deprecated'
  100 | #    define attribute_deprecated __attribute__((deprecated))
      |                                                 ^
3 warnings generated.
Compiling 3 files (.ex)
Generated xav app

The functions aren't used anywhere so maybe we can just remove them for now?

[mickel8]

Thanks!