inspect.c: fix -Wdangling-pointer warning

Untested.

examples/inspect.c|822 col 9| warning: storing the address of local
  variable 'ref_dec' in ‘img’ [-Wdangling-pointer=]

Change-Id: I142e2d31c4c71410f71ed94806c45bf8a9739b47
diff --git a/examples/inspect.c b/examples/inspect.c
index dca274f..9b2acea 100644
--- a/examples/inspect.c
+++ b/examples/inspect.c
@@ -773,6 +773,7 @@
 const unsigned char *frame;
 const unsigned char *end_frame;
 size_t frame_size = 0;
+struct av1_ref_frame ref_dec;
 
 EMSCRIPTEN_KEEPALIVE
 int read_frame(void) {
@@ -801,7 +802,6 @@
 
   int got_any_frames = 0;
   aom_image_t *frame_img;
-  struct av1_ref_frame ref_dec;
   ref_dec.idx = adr.idx;
 
   // ref_dec.idx is the index to the reference buffer idx to AV1_GET_REFERENCE