[llvm] [CI] Skip libcxx in non-llvm repo (PR #73282)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-github-workflow

Author: Jinsong Ji (jsji)

<details>
<summary>Changes</summary>

The new libcxx workflow are run and failing in non llvm repo.
Skip it similar to other workflow.


---
Full diff: https://github.com/llvm/llvm-project/pull/73282.diff


1 Files Affected:

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


``````````diff
diff --git a/.github/workflows/libcxx-build-and-test.yaml b/.github/workflows/libcxx-build-and-test.yaml
index 905906a1c75c935..dccfe54d4646767 100644
--- a/.github/workflows/libcxx-build-and-test.yaml
+++ b/.github/workflows/libcxx-build-and-test.yaml
@@ -43,6 +43,7 @@ env:
 
 jobs:
   stage1:
+    if: github.repository_owner == 'llvm'
     runs-on:
       group: libcxx-runners-8
     continue-on-error: false
@@ -81,6 +82,7 @@ jobs:
             **/CMakeOutput.log
             **/crash_diagnostics/*
   stage2:
+    if: github.repository_owner == 'llvm'
     runs-on:
       group: libcxx-runners-8
     needs: [ stage1 ]
@@ -130,6 +132,7 @@ jobs:
             **/CMakeOutput.log
             **/crash_diagnostics/*
   stage3:
+    if: github.repository_owner == 'llvm'
     needs: [ stage1, stage2 ]
     continue-on-error: false
     strategy:

``````````

</details>


https://github.com/llvm/llvm-project/pull/73282