Fix compile error on gcc

src/core/lib/channel/channel_args.c

@@ -213,7 +213,7 @@ static int find_compression_algorithm_states_bitset(const grpc_channel_args *a,
 
 grpc_channel_args *grpc_channel_args_compression_algorithm_set_state(
     grpc_channel_args **a, grpc_compression_algorithm algorithm, int state) {
-  int *states_arg;
+  int *states_arg = NULL;
   grpc_channel_args *result = *a;
   const int states_arg_found =
       find_compression_algorithm_states_bitset(*a, &states_arg);