[llvm] Add a scheduled build for libc++ (PR #73848)

[via llvm-commits]

https://github.com/EricWF created https://github.com/llvm/llvm-project/pull/73848

We had a scheduled build on buildkite, we probably want something testing head here as well.


>From d222ed5dfda14c0f912009026313039d4d9c9843 Mon Sep 17 00:00:00 2001
From: eric <eric at efcs.ca>
Date: Tue, 28 Nov 2023 01:31:12 -0500
Subject: [PATCH] Add a scheduled build for libc++

---
 .github/workflows/libcxx-build-and-test.yaml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index dccfe54d4646767..c2419579e3692c5 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -22,6 +22,9 @@ on:
       - 'runtimes/**'
       - 'cmake/**'
       - '.github/workflows/libcxx-build-and-test.yaml'
+  schedule:
+    # Run nightly at 8 AM UTC (or roughly 3 AM eastern)
+    - cron: '0 3 * * *'
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.event.pull_request.number }}