avfilter: Move ff_get_ref_perms_string() to where it is used.

This fixes a compilation failure with -DDEBUG.

libavfilter/avfilter.c

@@ -179,20 +179,6 @@ int avfilter_config_links(AVFilterContext *filter)
     return 0;
 }
 
-#ifdef DEBUG
-static char *ff_get_ref_perms_string(char *buf, size_t buf_size, int perms)
-{
-    snprintf(buf, buf_size, "%s%s%s%s%s%s",
-             perms & AV_PERM_READ      ? "r" : "",
-             perms & AV_PERM_WRITE     ? "w" : "",
-             perms & AV_PERM_PRESERVE  ? "p" : "",
-             perms & AV_PERM_REUSE     ? "u" : "",
-             perms & AV_PERM_REUSE2    ? "U" : "",
-             perms & AV_PERM_NEG_LINESIZES ? "n" : "");
-    return buf;
-}
-#endif
-
 void ff_dlog_link(void *ctx, AVFilterLink *link, int end)
 {
     if (link->type == AVMEDIA_TYPE_VIDEO) {

libavfilter/video.c

@@ -21,6 +21,20 @@
 #include "avfilter.h"
 #include "internal.h"
 
+#ifdef DEBUG
+static char *ff_get_ref_perms_string(char *buf, size_t buf_size, int perms)
+{
+    snprintf(buf, buf_size, "%s%s%s%s%s%s",
+             perms & AV_PERM_READ      ? "r" : "",
+             perms & AV_PERM_WRITE     ? "w" : "",
+             perms & AV_PERM_PRESERVE  ? "p" : "",
+             perms & AV_PERM_REUSE     ? "u" : "",
+             perms & AV_PERM_REUSE2    ? "U" : "",
+             perms & AV_PERM_NEG_LINESIZES ? "n" : "");
+    return buf;
+}
+#endif
+
 static void ff_dlog_ref(void *ctx, AVFilterBufferRef *ref, int end)
 {
     av_unused char buf[16];