[Crash-utility] Speed up list/tree '-s' output.

[Alexandr Terekhov]

Dave,

I've added support for recognition of strings/functions. Turned out that such logic
doesn't impose severe efficiency penalty.
Also I've changed logic according to your suggestions.
Please take a look at the updated patch:

https://raw.githubusercontent.com/hziSot/crash-patches/09fc7245631795ad6b73321991a4bd9c78b2bc7d/crash_speed_up_tree_list.patch

Thanks,
Alexandr.