cmdutils: only use libavresample when it is enabled

avprobe and avserver use cmdutils and do not strictly require libavresample.

cmdutils.c

@@ -406,7 +406,9 @@ int opt_default(void *optctx, const char *opt, const char *arg)
     char opt_stripped[128];
     const char *p;
     const AVClass *cc = avcodec_get_class(), *fc = avformat_get_class();
+#if CONFIG_AVRESAMPLE
     const AVClass *rc = avresample_get_class();
+#endif
 #if CONFIG_SWSCALE
     const AVClass *sc = sws_get_class();
 #endif
@@ -423,9 +425,11 @@ int opt_default(void *optctx, const char *opt, const char *arg)
     else if ((o = av_opt_find(&fc, opt, NULL, 0,
                               AV_OPT_SEARCH_CHILDREN | AV_OPT_SEARCH_FAKE_OBJ)))
         av_dict_set(&format_opts, opt, arg, FLAGS);
+#if CONFIG_AVRESAMPLE
     else if ((o = av_opt_find(&rc, opt, NULL, 0,
                               AV_OPT_SEARCH_CHILDREN | AV_OPT_SEARCH_FAKE_OBJ)))
         av_dict_set(&resample_opts, opt, arg, FLAGS);
+#endif
 #if CONFIG_SWSCALE
     else if ((o = av_opt_find(&sc, opt, NULL, 0,
                               AV_OPT_SEARCH_CHILDREN | AV_OPT_SEARCH_FAKE_OBJ))) {