PR 1250, backtrace from abort

[Daniel Jacobowitz]

Just as a note....

The fix for this is either to start using frame_unwind_address_in_block in
i386_frame_cache, or finding a more general location to use it.  Otherwise
Mark's uber new i386 prologue analyzer, analyzes the following function. 
Then everything loses.

I think a more general solution is in order; for frame_func_unwind to return
a function based on the PC is not correct in this situation.  Perhaps we
should revisit the idea of a flag indicate whether the resume address
is known-in-block (dummy frames, sigtramps) or maybe-just-after (normal
calls).

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer