[clang] [llvm] [PAC][Driver] Support `pauthtest` ABI for AArch64 Linux triples (PR #97237)

[Daniel Kiss via cfe-commits]

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@@ -0,0 +1,4 @@
+// RUN: %clang --target=aarch64-linux-pauthtest       --sysroot=%S/Inputs/multilib_aarch64_linux_tree -### -c %s 2>&1 | FileCheck %s
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DanielKristofKiss wrote:

Looks this is not used: "clang/test/Driver/Inputs/multilib_aarch64_linux_tree/usr/include/aarch64-linux-gnu/.keep"
BTW we could just add to the test:
`rm -rf %t.dir && mkdir -p %t.dir/multilib_aarch64_linux_tree/usr/include/aarch64-linux-gnu/ &&  mkdir -p %t.dir/multilib_aarch64_linux_tree/usr/include/aarch64-linux-pauthtest/` 

https://github.com/llvm/llvm-project/pull/97237