lavfi: fix signature for default_filter_name()

Return a const char *, fix warnings:
libavfilter/avfilter.c: In function ‘default_filter_name’:
libavfilter/avfilter.c:414:5: warning: return discards ‘const’ qualifier from pointer target type [enabled by default]
libavfilter/avfilter.c: At top level:
libavfilter/avfilter.c:419:5: warning: initialization from incompatible pointer type [enabled by default]
libavfilter/avfilter.c:419:5: warning: (near initialization for ‘avfilter_class.item_name’) [enabled by default]

diff --git a/libavfilter/avfilter.c b/libavfilter/avfilter.c
index dfa2d2b2206049c5f9429d2d0a6567d288a25f53..f8fc483bd983a343224ea1aec50de8e0e002cca5 100644 (file)
--- a/libavfilter/avfilter.c
+++ b/libavfilter/avfilter.c
@@ -410,7 +410,7 @@ static int pad_count(const AVFilterPad *pads)
     return count;
 }
 
-static char *default_filter_name(void *filter_ctx)
+static const char *default_filter_name(void *filter_ctx)
 {
     AVFilterContext *ctx = filter_ctx;
     return ctx->name ? ctx->name : ctx->filter->name;