patch 8.1.1261: no error for quickfix commands with negative range

Problem:    No error for quickfix commands with negative range.
Solution:   Add ADDR_UNSIGNED and use it for quickfix commands.  Make
            assert_fails() show the command if the error doesn't match.
diff --git a/src/quickfix.c b/src/quickfix.c
index e8c7829..c11436a 100644
--- a/src/quickfix.c
+++ b/src/quickfix.c
@@ -4828,12 +4828,25 @@
 }
 
 /*
- * Returns the number of valid entries in the current quickfix/location list.
+ * Returns the number of entries in the current quickfix/location list.
  */
     int
 qf_get_size(exarg_T *eap)
 {
     qf_info_T	*qi;
+
+    if ((qi = qf_cmd_get_stack(eap, FALSE)) == NULL)
+	return 0;
+    return qf_get_curlist(qi)->qf_count;
+}
+
+/*
+ * Returns the number of valid entries in the current quickfix/location list.
+ */
+    int
+qf_get_valid_size(exarg_T *eap)
+{
+    qf_info_T	*qi;
     qf_list_T	*qfl;
     qfline_T	*qfp;
     int		i, sz = 0;