Cast int to size_t before adding instead of casting the result.

Quiets PVS-Studio warning V1028.

plugins/sudoers/policy.c

@@ -796,7 +796,7 @@ sudoers_policy_store_result(struct sudoers_context *ctx, bool accepted,
 
 	/* We reserve an extra spot in the list for the effective gid. */
 	glsize = sizeof("runas_groups=") - 1 +
-	    ((size_t)(gidlist->ngids + 1) * (MAX_UID_T_LEN + 1));
+	    (((size_t)gidlist->ngids + 1) * (MAX_UID_T_LEN + 1));
 	gid_list = malloc(glsize);
 	if (gid_list == NULL) {
 	    sudo_gidlist_delref(gidlist);