Merge commit 'f160c6a18a574b4c7d063e0a748037cbbd9912ee'

* commit 'f160c6a18a574b4c7d063e0a748037cbbd9912ee':
  lavfi: do not segfault on NULL passed to avfilter_get_by_name()

Merged-by: Michael Niedermayer <michaelni@gmx.at>

libavfilter/avfilter.c

@@ -392,6 +392,9 @@ AVFilter *avfilter_get_by_name(const char *name)
 {
     AVFilter *f = NULL;
 
+    if (!name)
+        return NULL;
+
     while ((f = avfilter_next(f)))
         if (!strcmp(f->name, name))
             return f;