patch 8.1.0493: argv() and argc() only work on the current argument list

Problem:    argv() and argc() only work on the current argument list.
Solution:   Add a window ID argument. (Yegappan Lakshmanan, closes #832)
diff --git a/src/eval.c b/src/eval.c
index 7c462fb..e70bfd8 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -8193,9 +8193,7 @@
     tabpage_T	*tp)	/* NULL for current tab page */
 {
     win_T	*wp;
-    int		nr;
-
-    nr = (int)get_tv_number_chk(vp, NULL);
+    int		nr = (int)get_tv_number_chk(vp, NULL);
 
     if (nr < 0)
 	return NULL;
@@ -8218,6 +8216,20 @@
 }
 
 /*
+ * Find a window: When using a Window ID in any tab page, when using a number
+ * in the current tab page.
+ */
+    win_T *
+find_win_by_nr_or_id(typval_T *vp)
+{
+    int	nr = (int)get_tv_number_chk(vp, NULL);
+
+    if (nr >= LOWEST_WIN_ID)
+	return win_id2wp(vp);
+    return find_win_by_nr(vp, NULL);
+}
+
+/*
  * Find window specified by "wvp" in tabpage "tvp".
  */
     win_T *