[llvm] Fix dead link to paper in benchmarking documentation. (PR #69645)

[via llvm-commits]

https://github.com/sashafrolov created https://github.com/llvm/llvm-project/pull/69645

I noticed a dead link and fixed it. I'm pretty confident this is the right paper, since I've seen it cited in other computer architecture classes. Sorry for slightly screwy commit history, I don't use github that much.

>From 2c62a7b97396a4eaf4fa943fc074bf7fd6a499f6 Mon Sep 17 00:00:00 2001
From: Sasha <sasha07974 at gmail.com>
Date: Thu, 19 Oct 2023 14:52:36 -0700
Subject: [PATCH] Fix dead link to paper in benchmarking documentation

I noticed a dead paper link in this documentation. I am 90% sure this is the right paper since I have seen this paper cited in other computer architecture classes similar to the UPenn one that the link was originally from.
---
 llvm/docs/Benchmarking.rst | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/llvm/docs/Benchmarking.rst b/llvm/docs/Benchmarking.rst
index 0f88db745a6862d..fca80e239667bc2 100644
--- a/llvm/docs/Benchmarking.rst
+++ b/llvm/docs/Benchmarking.rst
@@ -11,8 +11,8 @@ noise as much as possible. How to do that is very OS dependent.
 
 Note that low noise is required, but not sufficient. It does not
 exclude measurement bias. See
-https://www.cis.upenn.edu/~cis501/papers/producing-wrong-data.pdf for
-example.
+https://users.cs.northwestern.edu/~robby/courses/322-2013-spring/mytkowicz-wrong-data.pdf 
+for example.
 
 General
 ================================