defaultopts.c: Minor simplification

This happens to avoid a compiler bug in the current GCC development
branch.

defaultopts.c

@@ -31,13 +31,13 @@ void set_default_mplayer_options(struct MPOpts *opts)
         .movie_aspect = -1.,
         .flip = -1,
         .vd_use_slices = 1,
-        .lavc_param = (struct lavc_param){
+        .lavc_param = {
             .workaround_bugs = 1, // autodetect
             .error_resilience = 2,
             .error_concealment = 3,
             .threads = 1,
         },
-        .input = (struct input_conf){
+        .input = {
              .config_file = "input.conf",
              .ar_delay = 100,
              .ar_rate = 8,