[PATCH 5/5] Add frame pointer unwinding for aarch64

[Ulf Hermann]

> Does every fp-only frame gets duplicated after a DWARF CFI frame?
> I'll look if I can better understand why that is.

The last thing I've tested on an actual aarch64 setup is what I'm 
removing in this change:

https://codereview.qt-project.org/#/c/191650/5/3rdparty/elfutils/backends/aarch64_unwind.c

As you can see, I'm setting PC to the thing I read from memory, not the 
value of the LR register. So I must have had the same problem when I 
wrote that.

Ulf