patch 9.0.0990: callback name argument is changed by setqflist()

Problem:    Callback name argument is changed by setqflist().
Solution:   Use the expanded function name for the callback, do not store it
            in the argument. (closes #11653)
diff --git a/src/quickfix.c b/src/quickfix.c
index 4c414e0..ca5b356 100644
--- a/src/quickfix.c
+++ b/src/quickfix.c
@@ -7633,7 +7633,11 @@
     free_callback(&qfl->qf_qftf_cb);
     cb = get_callback(&di->di_tv);
     if (cb.cb_name != NULL && *cb.cb_name != NUL)
+    {
 	set_callback(&qfl->qf_qftf_cb, &cb);
+	if (cb.cb_free_name)
+	    vim_free(cb.cb_name);
+    }
 
     return OK;
 }