Add a scheduled build for libc++

[EricWF]

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

[llvmbot]

@llvm/pr-subscribers-github-workflow

Author: Eric (EricWF)

Changes

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

---

Full diff: https://github.com/llvm/llvm-project/pull/73848.diff

1 Files Affected:

• (modified) .github/workflows/libcxx-build-and-test.yaml (+3)

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 }}