Fix a visual studio compile error

BUG=webrtc:12647

Change-Id: Ieab6c89b11a90124290fa1b9f0edbd8c63f35e7e

av1/encoder/rdopt.c

diff --git a/av1/encoder/rdopt.c b/av1/encoder/rdopt.c
index de234de..0c32fb4 100644
--- a/av1/encoder/rdopt.c
+++ b/av1/encoder/rdopt.c
@@ -5290,7 +5290,7 @@
                                -1,
                                -1,
                                { 0 },
-                               {} };
+                               { 0 } };
   for (i = 0; i < MODE_CTX_REF_FRAMES; ++i) args.cmp_mode[i] = -1;
   // Indicates the appropriate number of simple translation winner modes for
   // exhaustive motion mode evaluation