use systemtep to debug TLS var in glibc lib

[Frank Ch. Eigler]

kemi wrote:

>>> [...] Maybe the systemtap can't debug the TLS vars?

This is correct: we are missing some extensions to the translation
logic to handle the architecture-specific TLS constructs.
https://sourceware.org/bugzilla/show_bug.cgi?id=14013

- FChE