[llvm] [premerge] Route macOS build through a monolithic script to enable Job Summary (PR #211565)

[Arseniy Obolenskiy via llvm-commits]

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@@ -0,0 +1,40 @@
+#!/usr/bin/env bash
+#===----------------------------------------------------------------------===##
+#
+# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+#
+#===----------------------------------------------------------------------===##
+
+#
+# This script performs a monolithic build of the monorepo and runs the tests of
+# most projects on macOS. This should be replaced by per-project scripts that
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aobolensk wrote:

Replicated the approach from your PR

https://github.com/llvm/llvm-project/pull/211565