patch 8.2.3232: system() does not work without a second argument

Problem:    system() does not work without a second argument.
Solution:   Do not require a second argument. (Yegappan Lakshmanan,
            closes #8651, closes #8650)
diff --git a/src/misc1.c b/src/misc1.c
index e66f5a8..7d7f022 100644
--- a/src/misc1.c
+++ b/src/misc1.c
@@ -2359,7 +2359,7 @@
 
     if (in_vim9script()
 	    && (check_for_string_arg(argvars, 0) == FAIL
-		|| check_for_string_or_number_or_list_arg(argvars, 1) == FAIL))
+		|| check_for_opt_string_or_number_or_list_arg(argvars, 1) == FAIL))
 	return;
 
     if (argvars[1].v_type != VAR_UNKNOWN)