vdec/lavd: check_duration wrong cond

It was perhaps meant to advise frame threads if not enabled, not if
slice thread is not enabled.

src/video_decompress/libavcodec.c

@@ -923,7 +923,9 @@ static void check_duration(struct state_libavcodec_decompress *s, double duratio
             MOV_WIN_FRM, s->mov_avg_comp_duration * MS_IN_SEC, tpf * MS_IN_SEC,
             TIME_SLOT_PERC_MAX);
         const char *hint = NULL;
-        if ((s->codec_ctx->thread_type & FF_THREAD_SLICE) == 0 && (s->codec_ctx->codec->capabilities & AV_CODEC_CAP_FRAME_THREADS) != 0) {
+        if ((s->codec_ctx->thread_type & FF_THREAD_FRAME) == 0 &&
+            (s->codec_ctx->codec->capabilities & AV_CODEC_CAP_FRAME_THREADS) !=
+                0) {
                 hint = "\"--param lavd-thread-count=<n>FS\" option with small <n> or 0 (nr of logical cores)";
         } else if (s->codec_ctx->thread_count == 1 && (s->codec_ctx->codec->capabilities & AV_CODEC_CAP_OTHER_THREADS) != 0) {
                 hint = "\"--param lavd-thread-count=<n>\" option with small <n> or 0 (nr of logical cores)";