[llvm] [AArch64] Restore Z-registers before P-registers (PR #79623)

[Ben Vanik via llvm-commits]

benvanik wrote:

In debug builds this is hitting the following assert in the CRT, so it looks like this std::reverse is incorrect and just happens to be passing on libc++:
```
#if _ITERATOR_DEBUG_LEVEL != 0
template <class _Ty>
constexpr void _Verify_range(const _Ty* const _First, const _Ty* const _Last) noexcept {
    // special case range verification for pointers
    _STL_VERIFY(_First <= _Last, "transposed pointer range");
}
#endif // _ITERATOR_DEBUG_LEVEL != 0
```

https://github.com/llvm/llvm-project/pull/79623