[clang] [Clang] Add #pragma clang deprecated_header (PR #168041)

[Aaron Ballman via cfe-commits]

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@@ -0,0 +1,6 @@
+#ifndef DEPRECATED_HEADER_MSG_H
+#define DEPRECATED_HEADER_MSG_H
+
+#pragma clang deprecated_header("This is a shitty header")
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AaronBallman wrote:

That's not acceptable for us to commit.

https://github.com/llvm/llvm-project/pull/168041