[PATCH xserver] os: avoid uninitialized offsets in backtrace

[Adam Jackson]

On Thu, 2018-02-15 at 23:47 -0600, Jeff Smith wrote:
> When xorg_backtrace calls unw_get_proc_name and an error occurs, offset
> might not be set for the current frame.
> 
> Initialize offset for each frame so that the offset from another frame
> cannot be used inadvertently.

remote: I: patch #205104 updated using rev 272fa1817091117d078a22252a03d3161dfc7b0f.
remote: I: 1 patch(es) updated to state Accepted.
To ssh://git.freedesktop.org/git/xorg/xserver
   6f9d29040..272fa1817  master -> master

- ajax