[llvm] [PAC][llvm-readobj][AArch64][ELF] Support `GNU_PROPERTY_AARCH64_FEATURE_PAUTH` (PR #85231)

[Fangrui Song via llvm-commits]

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@@ -1756,6 +1752,26 @@ enum : unsigned {
   GNU_PROPERTY_AARCH64_FEATURE_1_GCS = 1 << 2,
 };
 
+// aarch64 PAuth platforms.
+enum : unsigned {
+  AARCH64_PAUTH_PLATFORM_INVALID = 0x0,
+  AARCH64_PAUTH_PLATFORM_BAREMETAL = 0x1,
+  AARCH64_PAUTH_PLATFORM_LLVM_LINUX = 0x10000002,
+};
+
+// Bit positions of version flags for AARCH64_PAUTH_PLATFORM_LLVM_LINUX.
+enum : unsigned {
+  AARCH64_PAUTH_PLATFORM_LLVM_LINUX_VERSION_INTRINSICS = 0,
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MaskRay wrote:

Where are these constants defined?

https://github.com/llvm/llvm-project/pull/85231