avcodec/codec_desc: add mime type for X-PixMap

Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavcodec/codec_desc.c

@@ -1596,6 +1596,7 @@ static const AVCodecDescriptor codec_descriptors[] = {
         .name      = "xpm",
         .long_name = NULL_IF_CONFIG_SMALL("XPM (X PixMap) image"),
         .props     = AV_CODEC_PROP_INTRA_ONLY | AV_CODEC_PROP_LOSSLESS,
+        .mime_types= MT("image/x-xpixmap"),
     },
     {
         .id        = AV_CODEC_ID_XWD,