patch 8.2.2461: Coverity warns for unchecked return value

Problem:    Coverity warns for unchecked return value.
Solution:   Add "(void)" to avoid the warning.

Author: brammool

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2461,
 /**/
     2460,
 /**/

src/vim9execute.c

@@ -897,11 +897,11 @@ allocate_if_null(typval_T *tv)
     {
 	case VAR_LIST:
 	    if (tv->vval.v_list == NULL)
-		rettv_list_alloc(tv);
+		(void)rettv_list_alloc(tv);
 	    break;
 	case VAR_DICT:
 	    if (tv->vval.v_dict == NULL)
-		rettv_dict_alloc(tv);
+		(void)rettv_dict_alloc(tv);
 	    break;
 	default:
 	    break;