[llvm] [BOLT][binary-analysis] Add initial pac-ret gadget scanner (PR #122304)

[Anatoly Trosinenko via llvm-commits]

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@@ -0,0 +1,46 @@
+// RUN: %clang %cflags -march=armv8.3-a -mbranch-protection=pac-ret %s %p/../../Inputs/asm_main.c -o %t.exe
+// RUN: llvm-bolt-binary-analysis --scanners=pacret %t.exe 2>&1 | FileCheck -check-prefix=CHECK --allow-empty %s
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atrosinenko wrote:

Redundant options:
```suggestion
// RUN: llvm-bolt-binary-analysis --scanners=pacret %t.exe 2>&1 | FileCheck %s
```

https://github.com/llvm/llvm-project/pull/122304