[clang] Update Clang extension criteria (PR #96532)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman created https://github.com/llvm/llvm-project/pull/96532

This updates Clang's extension criteria to explicitly mention impacts on other projects within the monorepo.

These changes were discussed in the following RFC: https://discourse.llvm.org/t/rfc-require-discussion-of-impact-to-monorepo-stakeholders-when-adding-new-clang-extensions/79613

>From a9663aca9fd5454eef2ea36284c6c690d1e44a12 Mon Sep 17 00:00:00 2001
From: Aaron Ballman <aaron at aaronballman.com>
Date: Mon, 24 Jun 2024 14:25:39 -0400
Subject: [PATCH] Update Clang extension criteria

This updates Clang's extension criteria to explicitly mention impacts
on other projects within the monorepo.

These changes were discussed in the following RFC:
https://discourse.llvm.org/t/rfc-require-discussion-of-impact-to-monorepo-stakeholders-when-adding-new-clang-extensions/79613
---
 clang/www/get_involved.html | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/clang/www/get_involved.html b/clang/www/get_involved.html
index 3fc688837d0bc..99fa03abb6234 100755
--- a/clang/www/get_involved.html
+++ b/clang/www/get_involved.html
@@ -126,6 +126,12 @@ <h2 id="criteria">Contributing Extensions to Clang</h2>
   extension is not broken by ongoing maintenance in Clang. The test suite
   should be complete enough that another compiler vendor could conceivably
   validate their implementation of the feature against it.</li>
+
+  <li>A support story for other impacted projects within the monorepo: If the
+  extension can impact other parts of the project (libc++, lldb, compiler-rt,
+  etc), the proposal needs to document the impact for these projects to fully
+  support the extension and what level of support is expected. The impacted
+  project communities need to agree with that plan.</li>
 </ol>
 
 </div>