Merge pull request #76779 from nate-chandler/rdar136943907

[Test] Mark unsupported for OS stdlib.

Author: nate-chandler

validation-test/SILOptimizer/rdar133969821.swift

@@ -4,6 +4,7 @@
 // REQUIRES: concurrency
 // REQUIRES: concurrency_runtime
 // UNSUPPORTED: back_deployment_runtime
+// UNSUPPORTED: use_os_stdlib
 
 class C {
   init() {}