Fix argv leak on Unrecognized input file type err

Free argv (allocated by argv_dup) after the
"Unrecognized input file type" error.

Change-Id: If0c00e3ada53f436bf7408e765de4d84152f0892

apps/aomdec.c

diff --git a/apps/aomdec.c b/apps/aomdec.c
index acecc90..8b149a0 100644
--- a/apps/aomdec.c
+++ b/apps/aomdec.c
@@ -628,6 +628,7 @@
 #if !CONFIG_WEBM_IO
     fprintf(stderr, "aomdec was built without WebM container support.\n");
 #endif
+    free(argv);
     return EXIT_FAILURE;
   }