[compiler-rt] [compiler-rt] DumpAllRegisters implementation for windows arm64. (PR #112254)

[Mike Hommey via llvm-commits]

glandium wrote:

The winnt.h header in the windows 10 SDK 10.0.22621 has this:
```
    /* +0x008 */ union {
                    struct {
                        ...
                        DWORD64 X28;
    /* +0x0f0 */        DWORD64 Fp;
    /* +0x0f8 */        DWORD64 Lr;
                    } DUMMYSTRUCTNAME;
                    DWORD64 X[31];
                 } DUMMYUNIONNAME;
    /* +0x100 */ DWORD64 Sp;
    /* +0x108 */ DWORD64 Pc;
```

https://github.com/llvm/llvm-project/pull/112254