[llvm] [BOLT][AArch64] Do not crash on authenticated branch instructions (PR #129898)

[Anatoly Trosinenko via llvm-commits]

atrosinenko wrote:

```
        adrp    x8, jumpTable
        ldr     x8, [x8, #3656]
        ldr     x8, [x8, x0, lsl #3]
        blr     x8
```
looks like a natural way to express
```cpp
       const int result = jumpTable[option]();
       printf("result %d\n", result);
```
in machine code, as `blr` calls a function here. I think such hand-written emulation of jump tables is far out of scope for `analyzeIndirectBranchFragment`. 

https://github.com/llvm/llvm-project/pull/129898